*.js.jsx does not get compiled.

[nsallis]

When writing xyz.js.jsx files, middleman build fails with

error  build/ads/react_ad_test/main.js
undefined local variable or method `path'

It does work if I leave it as xyz.jsx, but then the produced file is named just xyz, not xyz.js

note, if the asset is names only xyz.jsx, it does build correctly!