adds additional info to footer

- github (for our project) and twitter (the city’s account)
footer styling

- shamelessly pilfering (and perhaps butchering) some ideas from Transitmix.net

- adding a little back and forth swaying animation for the twitter bird for fun.
make animation just a wee bit faster

- Livien said it was a little too subtle
add top border on footer 

- helps clarify relationship between spaces (as in, marks them as separate).
underline links but not links when they’re buttons
provide more space for footer contents
more subtlety in drop shadow

- thanks Maya, Manya
Merge pull request #33 from codeforamerica/frontend/fun-footer

updated footer content + styling