Refactor JsonFailure app.

* Add check for :html format.
* Fix incorrect content_type for :json format.
* Change name to CustomFailureApp to reflect changes.
Add staging environment file.

* Make sure to specify the Heroku url in .git/config as well.
Add ActionMailer host URL for production.rb environment.
Update FOG credentials to use staging rather than test name convention.

As it stands, evermarktest is a representation of the staging environment.
Fix typo for ng-show dribbble "Unlink" button.
Merge branch 'add-unlink-4' into handle-html-auth-failures-2
Merge branch 'master' into handle-html-auth-failures-2
Merge pull request #13 from vitaliyg/handle-html-auth-failures-2

Handle html auth failures 2