Add Symbol keyword for ES6
Merge pull request #183 from Cryrivers/master

Add Symbol keyword for ES6
Don't run coffee with -m option if source maps disabled

This makes the plugin work with older versions of the Coffeescript compiler,
which don't support the -m option.

Fixes #185
Merge pull request #186 from alexdowad/m-option-fix

Don't run coffee with -m option if source maps disabled
Merge remote-tracking branch 'upstream/master'