changes recommended by code climate.
Merge pull request #17 from rdepena/feature/code_climate_changes

changes recommended by code climate.
adds support for missing ds4 buttons, tests and coverage
small tidy up
Merge pull request #18 from achingbrain/master

Adds support for missing ds4 buttons, tests and coverage
DS4 Improved support Thanks to @achingbrain
refactoring the linux connector.
Merge branch 'master' of https://github.com/rdepena/node-dualshock-controller into feature/linux_bt_compatibility
clean up post refacored code.