Use ExtractTextPlugin as styleLoader for bootstrap-sass and font-awesome

[p-a]

It seems that the integration of bootstrap-sass and font-awesome introduced some Flash Of Unstyled Content in the production build. Or rather no styling at all with javascript disabled.
Solution was to use the ExtractTextPlugin as style-loader for the loaders so that the final styling got appended to the main css file, rather than becoming a javascript rendered style tag.
Perhaps there exists better ways of having separate loader configurations for dev and prod, but this PR comes with two new files, allowing for more to things to be overridden if needed.
Works for me, but then I'm quite new to webpack :)

[erikras]

@halt-hammerzeit, can you verify this?

[catamphetamine]

Well, regarding Bootstrap and Font-Awesome: I didn't use any of them.
For production, it's obvious (he he, actually that's a pretty advanced topic) that ExtractTextPlugin must be used otherwise there would be a flash of unstyled content indeed.
I guess this PR nails a bug introduced by a contributor who didn't test his PR too thoroughly.

[erikras]

Sounds like an endorsement to me. :-)

[catamphetamine]

@erikras yeah, forgot to clarify that

[trueter]

I wasn't aware of this either. Thanks @p-a!

[p-a]

@trueter: I'm glad I could help!