Fixes #109 - aligns buttons.

- Footer buttons were misaligned. This commit adjusts the CSS to align
the buttons. Also consolidates some of the button CSS.
- Additionally, chevrons on the agencies view were too low. This commit
reduces the top padding to better vertically align them.
Merge pull request #110 from codeforamerica/109-align-buttons

Fixes #109 - aligns buttons.