Add index.js with fancy conditional loading possibilities.
Assign methods directly to prototype instead of mixing object into prototype.
Change dynamic index imports to CapCase, they're constructors.
Split cluster stuff out of lib/less-cluster.js > lib/master.js
Split cluster stuff out of lib/less-worker.js > lib/worker.js
Executable should instantiate LessCluster.Master
Switch back to mocha, with chai + sinon.

 - Adds pre-test jshint and post-test coverage check.
Merge branch 'master' into dependency-filtering

Conflicts:
	lib/less-cluster.js