Bootstrap 3 WIP

Still a WIP, but wanted to put it up to get some feedback.

To keep this diff clean, I'll delete /static/css/less_css/less/bootstrap/ and /static/css/less_css/less/tba_bootstrap_overrides/ later.

The only Bootstrap LESS file edited should be variables.less

New (aside from everything Bootstrap 3 has to offer):
- Had a bit of fun with the navbar styling :wink: 
- "Scroll to top" button appears on the bottom right for small devices
- Year list on Event List and Insights pages stays on the side when scrolling
- Did a bit of reorganizing of our LESS files

Still requires work:
- GameDay (this really only uses Bootstrap dropdowns...)
- Chose to get rid of our old custom nav-stacked-phone class (used for jumping to weeks on the Event List page and for jumping to Events on Team Details pages). Was thinking about doing a [scrollspy](http://getbootstrap.com/javascript/#scrollspy) kind of thing...

Screenshots:
![the blue alliance](https://f.cloud.github.com/assets/1421884/943714/452994e0-0253-11e3-9ea4-ec0d23de646e.png)
![the blue alliance admin](https://f.cloud.github.com/assets/1421884/943715/4a3e35b2-0253-11e3-86c6-44fba1c309f5.png)