Register options

Open username-removed-861968 requested to merge moisadoru/buble:register-options into master

Split as a separate merge request from !102 (merged).

I needed a way to be able to pass --no modules when using the register script as a mocha compiler (

The two environment variables (BUBLE_OPTION_YES and BUBLE_OPTION_NO) are the equivalents of the --no and --yes command line switches.