Load modules from the mongo modulestore as errordescriptors if creating a regular descriptor fails, but leave the location the same

Make imports into the CMS ignore broken modules, while still loading bad xml as error modules in the LMS

Make ErrorDescriptor continue to use the interface for __init__ that XModuleDescriptor uses, while providing a helper function for constructing from a different set of arguments

Move common code for updating modules in mongo to a single helper function that also handles creating the item if it doesn't already exist

optimize!

Also make the actual ?next redirection work with caching

- use js instead of django to do the redirection

Fix login-if-?next behavior

fix up syllabus

make progress label wider

Kimth/fix gradebook

* for more context, see https://basecamp.com/1892446/projects/631155-devops/messages/4719963-strange-caching

Fix forums in IE9; apparently it's just very strict about the charset be...

Fix forums in IE9; apparently it's just very strict about the charset being a valid identifier. utf8 is not a valid identifier, utf-8 is.

Feature/arjun/minor style changes

Some 188-specific styling + default styling for static tabs