Bug 896297 - New profile builder api.

New command line option --profile-builder X to replace profile builder.
New command line option --profile-base X used to set the default profile preferences.
Simplify Mocha binary path resolution

Additionally, increase cross-platform compatability through consistent
use of `path.join`.
actually install gjslint
Add some documentation and turn on more gjslint errors
Address review comments
Merge branch 'bug-896297-cleanup' of github.com:gaye/marionette-js-runner into profile-builder-api

Conflicts:
	bin/marionette-mocha
	lib/childrunner.js
	lib/parentrunner.js
linter fix
another doc fix
Merge pull request #11 from lightsofapollo/profile-builder-api

Bug 896297 - Profile builder api