MUMUP-1402: Collapsible Sidebar

Youtube-esque collapsible sidebar. The sidebar is shown by default, since it I don't think it would be smart to relegate the navigation for the sight to a small menu icon by default. 

Still need to add the ability to remember whether sidebar is open or closed per user. I believe that's on the uPortal side though?

### Notable tweaks:
- Mobile menu now has this black and white image of campus instead of the crest
- Quick links added to the sidebar as a concept for how this could look. I am personally a huge fan of this approach, but I know Phyllis had reservations about it.
- Marketplace icon is a star. Cog icon didn't really make sense to me.
- When sidebar is minimized, the width of the main content is col-sm-11, rather than col-sm-10. Hurray for more real estate!

I took some liberties with the style, let me know if you have any thoughts/concerns/suggestions for them.

### Screenshots:
![image](https://cloud.githubusercontent.com/assets/1919535/5480671/03ac913a-860e-11e4-92f6-13a6fb0ac515.png)

![image](https://cloud.githubusercontent.com/assets/1919535/5480683/1c93eafe-860e-11e4-8f2d-69a83bcdab8b.png)

![image](https://cloud.githubusercontent.com/assets/1919535/5480687/2cb2b1cc-860e-11e4-876b-b592e03189fe.png)

![image](https://cloud.githubusercontent.com/assets/1919535/5481366/c90f2e40-8615-11e4-9a44-7b5ac6f96e54.png)


We could move this padding thing to line 22 of sidebar.less