Revert to getNodeExecutablePath

Due to an issue in Atom, BufferedNodeProcess does not produce any output, resulting in no linting occurring. For now, revert back to BufferedProcess and getNodeExecutablePath
Merge branch 'master' of github.com:glek/Linter into glek-master

Conflicts:
	lib/linter.coffee
Merge branch 'glek-master'

Tested this with csslint, pylint, coffeelint on OS X and everything seemed to
work. Since this apparently fixes issues for Windows users, I'm merging it in.