Match .jsx anywhere in the filename

Might it be helpful to match files that have `.jsx` anywhere in their filename?

I myself have a build system that parses Coffeescript, then JSX. I name my files `foo.jsx.coffee`.

Without this patch, I have to do the following in `brunch-config.coffee` (which might be good enough):

    ReactCompiler = require 'react-brunch'
    ReactCompiler::pattern = /\.jsx/

Thoughts?
Merge pull request #1 from steveluscher/patch-1

Match .jsx anywhere in the filename