Added Mailchimp integration for sponsors.
Fixes form error display on sponsors form.
Makes sure Gibbon does not break when there is no API key set.
Adds test for SponsorsController Mailchimp integration.
Merge pull request #19 from devbootcamps/mailing-lists

Sponsor Mailing lists
initial speakers page, changes in navigation
adds speakers page
moves about us to the bottom of footer list
Added speakers form and admin.