and without rewriting static links.  changes xml_importer.py and
import.py

Add Draft module store that is used whenever any item is update in the CAS (but not during import, and not for templates)

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

Acknowledge the fact that right now keystore is really just a module store. If we need a keystore that returns other objects, we can reexctract the base class into it's own module again

Make location into a named tuple, and use it more as a first class entity, rather than URL for identifying content

Move the resources_fs abstraction into the primary DescriptorSystem, as it is needed for more than just XMLParsing

Revert "Make import work via mako again, to unblock others while I work on making the LMS work using XModuleDescriptors"

This reverts commit 6fdf44fe.

Make import work via mako again, to unblock others while I work on making the LMS work using XModuleDescriptors

Remove semantically meaningless sections from course.xml by moving their attributes onto the contained element. If there is more than one contained element, turn the section into a sequence. Also handles includes

Also:
Render all XModuleDescriptors in the cms the same way
Default them to editing raw xml, if there is no specific module for them

Add categories and XModuleDescriptors for all module types that are used at the top level of a course

Add categories and XModuleDescriptors for all module types that are used at the top level of a course