New Front Page

Huge revamp to the visual design of Eduki. This design mainly focuses on the front page, but there have been minor changes to other pages to compensate for these new changes.

* New front page design
* Front page now has login/signup
* *Very* basic about page...
* Non-logged in users will now be redirected here if they try to access a user-required page
* New navbar design
* All main page templates now have a `.container` `div` so it is not longer in the application.html.erb
* All the tests for login/signup have been merged into the index tests. 
* No more responsive design
* Error popovers when a user enters in invalid credentials

@DavidMah @abboudm