ES6 npm modules not supported

[chrischen]

If an ES6 npm module is imported gluestick currently ignores it due to the default ignoring of all node_modules files.

Attempted workaround prepending "compiled" as in import something from 'compiled/package' to force it to go through babel, however this does not seem to work and causes the ES6 code to leak into the static bundle, as well as causes uglify to fail (the bundled uglify version doesn't support ES6 minification).