Rocha doesn't work with compilers

Attempting to do the following:

`rocha ./test/**/**/*.jsx --recursive --compilers js:babel-core/register`

This returns a syntax error since it doesn't recognize the ES6 syntax. Have also tried this with a coffeescript compiler with the same result. Would love to use this but need compiler support.

Start by reproducing the documented `rocha ./test/**/**/*.jsx --recursive --compilers js:babel-core/register` command and inspect how the CLI handles the `--compilers` option. Compare the ES6/JSX failure with the reported CoffeeScript failure; done means compiler support works for these test inputs without the syntax error.

Written by the indexing model from the issue text.