refactor(lib/cli.coffee): Reimplement code handling CLI option `--reporters`
refactor(lib/cli.coffee): Reimplement code handling CLI option `--reporters`

Existing code was literally copied from Mocha. Now instead of pretending to be Mocha, we tell Mocha
to handle it. Little more awkward than hoped as option is handled within script rather than by its
module export.

cybertk/abao