Re theme

This commit includes a re-working of the css and share control 

* [x] Controls look blank/broken on Retina
* [x] Test in :white_check_mark: ~~IE8~~, :white_check_mark: ~~IE9~~, :white_check_mark: ~~IE10~~
* [x] If there's a new build process and requirements for generating icons, it needs to be documented and explained for people new to the project.

#### CSS
- Consistify colors
- Use the border-box model throughout
- Consistify Leaflet controls and ui
- Sprite icons #364 
- Contain font sizes to the highest level and avoid defining specific cases so they may be overridden more easily 
- Removed the IE stylesheet. Fix up cases where this was needed or write in the changes to a browser section at the bottom of the stylesheet.
- Remove duplicate max-width #501

#### Share Control
- Add a pinterest share button
- Rewrite how the share modal is added to the page
- Fix up the event binding #514