Improve debuggability when call-count numbers don't match up
Add test to verify bad query behavior of xblock_handler
Add memoization for has_changes
Pre-cache has_changes when computing ancestors
Merge pull request #5020 from edx/hotfix/reduce-studio-mongo-calls

Hotfix - reduce number of Studio mongo calls
Merge branch 'release' into andya/merge-hotfix-2014-08-29

Conflicts:
	cms/djangoapps/contentstore/tests/test_import.py
	common/lib/xmodule/xmodule/modulestore/__init__.py
	common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py
	lms/djangoapps/courseware/tests/test_module_render.py
Merge branch 'release' into andya/merge-hotfix-2014-08-29

Conflicts:
	cms/djangoapps/contentstore/tests/test_import.py
	common/lib/xmodule/xmodule/modulestore/__init__.py
	common/lib/xmodule/xmodule/modulestore/tests/test_mixed_modulestore.py
	lms/djangoapps/courseware/tests/test_module_render.py
Merge remote-tracking branch 'edx/master' into andya/merge-hotfix-2014-08-29
Tweak mongo count numbers
Merge pull request #5031 from edx/andya/merge-hotfix-2014-08-29

Merge hotfix-2014-08-29 to master