0.2.1

Fixes

• Handle errors for turnOff in blinkWorker
• Fix potential undefined callback error in custom serialiser wrapper
• Only reconfigure git username & email when running on Travis during gh-pages publishing

New features

• Improve error messages a bit
• Implement .setBrightness()
• Override .valueOf() to return current brightness [feedback needed]
• Override .toString() on instance objects to be more helpful