Added the skeleton to implement materials.
Sorry, syntax errors while reformatting.
This migration really works now.

Conflicts:
	db/schema.rb
Properly compute the number of new materials uploaded. Also make sure that the materials have the last update/create timestamps stored (like a normal filesystem)
Only return the top-level materials folders when enumerating the folders belonging to a course.
Simplify the design a little; allow only one root folder per course.
Handle the situation where a course does not have any folders or materials defined.
Basic templates for folder listings. Doesn't actually list, for now.
Show and index for the materials controller should give a folder listing.
I can get away with 1 controller and 1 view for materials folder listings.
Fix listing different subfolders with IDs.
Fix new material route.
Yay, I got the nav bar to work.
At every folder listing, we can upload a file or we can create a subfolder.
Change Materials page to match Mission page.
Follow RESTful principles: index will show a listing, show will get the actual material.
Implemented listing subfolders.
Implemented full display of folder contents.
Implement display of the real file name of an uploaded file.
Implement display of the file size.