Delete the Give Feedback banner

[dasaderi]

With the request of adding an extension banner to the site (PR #168), there was a discussion around the fact that there are too many call to action on the front page. Josh, Georgia and I discussed this and think we should get rid of the Give Feedback banner and update the About with a call to feedback there (for which I made another issue #170.

[dasaderi]

Not a priority right now.