First pass at getting the data.gov redesign theme in place.

More cleanup is needed for the layout of api.data.gov, but I think this
at least gets the template in place.
Cleanup the layout for the new redesign.

Also, drop the community page, since it wasn't particularly relevant any
more, and add a 404.html page for github pages 404 handling.
Fix layout of beta banner to better work on the redesign.

- Move the banner lower, so it doesn't overlap with the header
  navigation on narrower screens and also to make it look more related
  to api.data.gov
- Adjust styles and colors so it's fits a bit better with the flatter
  redesign.
Add link to Data.gov's CKAN API and try to clarify this service.
Add link to FBOpen's API since it's using this service.
Initial signup form implementation as an client-side embeddable widget.
Capture unexpected signup errors with rollbar.
Show message while loading embeded content.
Only enable rollbar in the build version.
Client-side error validation for the embedded signup form.

Also fix rollbar in development mode.
Fix IE 8 and 9 compatibility with signup process. Other cleanup.
Fix odd compilation issue in the embed stylesheet.
Setting up for production use. Enable sending welcome e-mails.
Merge remote-tracking branch 'origin/master' into redesign
Merge pull request #42 from GSA/redesign

data.gov theme redesign