Windows server unit tests for fs are failing

[liza-mae]

The following tests are failing for the windows fs:

1. dev/build/lib/fs copy() copies the mode of the source file:
   Error: expected '666' to equal '777'
   at Assertion.assert (node_modules\expect.js\index.js:96:13)
   at Assertion.be.Assertion.equal (node_modules\expect.js\index.js:216:10)
   at Assertion.(anonymous function) [as be] (node_modules\expect.js\index.js:69:24)
   at Context.it (C:/Users/vagrant/kibana/src/dev/build/lib/tests/fs.js:187:45)
   at

2. dev/build/lib/fs copyAll() copies files and directories from source to dest, creating dest if necessary, respecting mode:
   Error: expected '666' to equal '777'
   at Assertion.assert (node_modules\expect.js\index.js:96:13)
   at Assertion.be.Assertion.equal (node_modules\expect.js\index.js:216:10)
   at Assertion.(anonymous function) [as be] (node_modules\expect.js\index.js:69:24)
   at Context.it (C:/Users/vagrant/kibana/src/dev/build/lib/tests/fs.js:228:78)
   at

3. dev/build/lib/fs copyAll() supports atime and mtime:
   Error: expected 113214397141.89111 to be below 86400000
   at Assertion.assert (node_modules\expect.js\index.js:96:13)
   at Assertion.lessThan.Assertion.below (node_modules\expect.js\index.js:313:10)
   at Function.below (node_modules\expect.js\index.js:499:17)
   at Context.it (C:/Users/vagrant/kibana/src/dev/build/lib/tests/fs.js:285:63)
   at
   at process._tickDomainCallback (internal/process/next_tick.js:228:7)

Part of issue: #21315