Attempt to fix some of the generate_data.sh warnings.
bower.json: sort deps by name.
Update main.css.

* switch to class
* change selectors order; put tags on top
Move inline style to main.css.
Simplify a couple of shorthands.
Remove unused selectors.
Make use of Bootstrap's `pull-right` and `pull-left` classes.

Also merge conditionals and fix indentation.
Remove relative URL.
Losslessly compress images.

Before: 2164 bytes
After:   750 bytes
Use Font Awesome icons instead of PNG files.
Fix validation errors.

Switch to a `ul` for the navbar items.
Update Font Awesome to v4.0.3.
frontend/README.md: Remove obsolete info about Ruby/Compass.