Assets bundle with funnel

Complete revamp of assets management! Now, css/js files as split so it is much easier for others to work on it.

What is new:
 - we are using flask-funnel for assets minifying (thanks @EmilyDirsh for the tip)
 - assets are minified during deploy phase after each `git push` (no action required here)
 - ./start-devel.sh now accepts DEBUG=[0|1] env var so it will compile (0) or not (1) assets on the fly.

Running in production will always compile assets, unless DEBUG=1 is set on env of the gear.
Files are generated inside `wsgi/static/bundles/{js,css}`, so templates will load them from there, otherwise files are loaded one by one (not bundled) when DEBUG=1 from `wsgi/statis/{js,css}`.