[WIP] New TEMPORARY frontend theme

**PLEASE DO NOT REVIEW THE CODE**...

Before you freak out and say "why thiiiss isss so uglyyy?", I decided that we should wait a bit with hiring the designer to do this, for various reasons...

This is my quick attempt to make the frontend look more like a very basic shop than an ugly bootstrap prototype. I think it's better than what we have now, and gives us good base to prototype features, without scaring people with the default Bootstrapish look (which is nice, but it's EVERYWHERE). 

I deployed this branch to http://demo.sylius.org/ if you want to have a look. Still there is some stuff to do, but at least you can tell me if push this forward or throw away.

PS. Yeah, the idea is that these blocks in bottom (as well as standalone pages) will be editable via CMF.