Split base.html into sidebar.html and plain.html

* sidebar.html has a 3 column sidebar on the right
* plain.html contains a 12 column content area
Update template inheritance for templates
Move row div to sidebar and plain templates
Add a missing </div>
Rename "main" block to "content"

This will help with compatibility with other apps.
Update home page to use sidebar template
Remove most of page_setup.js
Add simple-sidebar.css
Add forgotten modal block
Fix media url in urls.py
Remove superfluous container
Fix registration sidebar button
Use new version of Font Awesome
Fix sidebar whitespace
Fix sidebar up with an accordion
Allow users to click the accordion panel header

Also show pointer cursor when hovering over the accordion
Clean up home page sidebar
Fix template issues
Fix templates for flat pages
Clean up more templates