Fix TypeError during tests.

[ksdme]

When npm run test is run, it causes a:

TypeError: Cannot read property 'dispose' of null
	at LanguageClient.cleanUp (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:647:30)
	at LanguageClient.stop (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:621:14)
	at LanguageClient.handleConnectionError (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:882:18)
	at errorHandler (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:744:19)
	at /home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:47:42
	at CallbackList.invoke (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:103:39)
	at Emitter.fire (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:167:36)
	at writeErrorHandler (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/main.js:113:22)
	at CallbackList.invoke (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:103:39)
	at Emitter.fire (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:167:36)
	at StreamMessageWriter.AbstractMessageWriter.fireError (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/messageWriter.js:28:27)
	at Socket.<anonymous> (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/messageWriter.js:60:67)
	at emitOne (events.js:96:13)
	at Socket.emit (events.js:191:7)
	at onwriteError (_stream_writable.js:341:10)
	at onwrite (_stream_writable.js:359:5)
	at fireErrorCallbacks (net.js:480:13)
	at Socket._destroy (net.js:489:5)
	at Socket._writeGeneric (net.js:692:10)
	at Socket._write (net.js:743:8)
	at doWrite (_stream_writable.js:329:12)
	at writeOrBuffer (_stream_writable.js:315:5)
	at Socket.Writable.write (_stream_writable.js:241:11)
	at Socket.write (net.js:670:40)
	at StreamMessageWriter.write (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/messageWriter.js:72:27)
	at /home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/main.js:414:35
	at Promise (<anonymous>)
	at Object.sendRequest (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/main.js:402:26)
	at Object.shutdown (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:60:51)
	at /home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:624:24
	at <anonymous>
	at process._tickCallback (internal/process/next_tick.js:109:7)

TypeError: Cannot read property 'dispose' of null
	at LanguageClient.cleanUp (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:647:30)
	at LanguageClient.stop (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:621:14)
	at LanguageClient.handleConnectionError (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:882:18)
	at errorHandler (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:744:19)
	at /home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:47:42
	at CallbackList.invoke (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:103:39)
	at Emitter.fire (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:167:36)
	at writeErrorHandler (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/main.js:113:22)
	at CallbackList.invoke (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:103:39)
	at Emitter.fire (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/events.js:167:36)
	at StreamMessageWriter.AbstractMessageWriter.fireError (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/messageWriter.js:28:27)
	at Socket.<anonymous> (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/messageWriter.js:60:67)
	at emitOne (events.js:96:13)
	at Socket.emit (events.js:191:7)
	at onwriteError (_stream_writable.js:341:10)
	at onwrite (_stream_writable.js:359:5)
	at fireErrorCallbacks (net.js:480:13)
	at Socket._destroy (net.js:489:5)
	at Socket._writeGeneric (net.js:692:10)
	at Socket._write (net.js:743:8)
	at doWrite (_stream_writable.js:329:12)
	at writeOrBuffer (_stream_writable.js:315:5)
	at Socket.Writable.write (_stream_writable.js:241:11)
	at Socket.write (net.js:670:40)
	at StreamMessageWriter.write (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/messageWriter.js:74:27)
	at /home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/main.js:414:35
	at Promise (<anonymous>)
	at Object.sendRequest (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-jsonrpc/lib/main.js:402:26)
	at Object.shutdown (/home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:60:51)
	at /home/ksdme/Work/gsoc/coala-vs-code/node_modules/vscode-languageclient/lib/main.js:624:24
	at <anonymous>
	at process._tickCallback (internal/process/next_tick.js:109:7)

Need to research and fix the reason behind this.