adding logo png

here you go bro
Merge branch 'gh-pages' of https://github.com/codeforamerica/workforamerica into gh-pages
Merging changes
* 'gh-pages' of https://github.com/codeforamerica/workforamerica:
  Creating README.md
  Slight style tweaks.
  homepage styles
  adding logo png
  Update index
  Update styles
  Update markup and stuff