SplitMongo, template refactoring, pep8 changes, and other fixes

Mashed into one big commit hopefully w/ refactoring to the xmodule
refactoring into xblocks.
Adjust for the xmodule init method refactoring on master

move category and location into module data content as hardcoded
specially treated fields
Fix a few tests using templates rather than categories.
Don't hardcode path to mongoimport.
Explicitly set rerandomize for test cases