Add sponsors to footer

Fixes #2063
Merge pull request #2079 from jalyna/sponsors-in-footer

Add sponsors to footer
Add bugsnag to API side of things
Bugsnag's rack middleware is superfluous
Tweak readme
Add db setup tasks, update README
Merge pull request #2082 from nateberkopec/db-tasks

Add db setup tasks, update README
missing end in rake task
Merge pull request #2083 from castlese/db-tasks-bug

missing end in rake task
Add links between nits pages