* More tests for mongo modulestore, including tweaks to test files
* add location_to_id method to CourseDescriptors
* Implement path_to_location method in mongo.py
- TODO: does not handle position in sequences yet.
* fix bug in jump_to view.
* Clean up test data for simple, toy courses
* clean up test_mongo.py
* write initial test for path_to_location
* hook up view to use path_to_location
Next: actually implement it :)
* change custom tags in test/data/full to new single-tag format
* fix broken file references
* fix argument to import_from_xml
* error_handler fix in mongo.py in next commit