CSStweaks3

This pull request implements a number of minor changes:
1. Positions the search icon slightly to the right so it is not cut off like this:
![fixsearchicon](https://cloud.githubusercontent.com/assets/521978/3892936/9d8a1a70-2236-11e4-895a-8ea6d4c93fa0.png)
2. Redesigns form focus state to use blue border and white background rather than yellow. https://github.com/hypothesis/h/issues/1388
3. Fixes spacing between buttons and inputs on the annotation editor:
![toomuchspace](https://cloud.githubusercontent.com/assets/521978/3892961/e19c0322-2236-11e4-95e4-006a7d1cfada.png)
4. Changes 'Private' privacy option to 'Only Me,' repositions the lock icon to be closer to where privacy options are selected, adds icons to the privacy dropdown menu, and adds the .selected class to the currently selected level in the privacy dropdown. This addresses 
https://github.com/hypothesis/h/issues/1377 and looks like so:
![currentinterface](https://cloud.githubusercontent.com/assets/521978/3893026/63b30900-2237-11e4-8db2-bc5db1ca76b9.png)
![iconsfordropdown](https://cloud.githubusercontent.com/assets/521978/3893030/67431e02-2237-11e4-875a-a37ec7792351.png)
5. General CSS cleanup and organization. Creates vender folder for 3rd Party CSS files. 
I see that this was done to take the extra space above the save/cancel buttons away.

I've gone ahead and just stripped that margin off the form-actions class instead. If it's desireable to have this margin on the auth forms it should be special cased there. Otherwise, I think it's liable to cause confusion having the buttons for the annotation form use the form action styles but lack the namespace at their root.