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
The main django template needs header and footer feature flags.
Create shard 3 for bok-choy; handle unknown shards.

This accomplishes three things:
1. Create a 3rd bok-choy shard
2. Allow the script to run 'all' shards
3. If the script receives an unknown shard, it will pass through empty tests.

The last one (3) is intended to allow us to expand to additional shards
on our Jenkins infrastructure. If we have, for example, a 4th shard introduced,
but someone attemps to run a commit that is older (and therefore still
has 3 shards); the script will just pass-through shard '4'. This means
older commits can still get tested. In that case, the older commit
will still test all cases, because the last shard (n) is basically an
'everything else' shard.
Split Bok-Choy Tests into 3 shards
TE-447
Cleaning up ddt syntax for new footer test.
Merge remote-tracking branch 'edx/master' into andya/merge-hotfix-2014-08-29
Tweak mongo count numbers
AWS settings for XBlocks to have filesystem-like storage
Merge pull request #5036 from edx/sanchez/fix_django_header_tests

Sanchez/fix django header tests
Merge pull request #4988 from edx/benp/all-tests-update

jenkins scripts: provide 'all' shard for bok-choy, use as default.
Merge pull request #5039 from edx/pmitros/aws-djpyfs

AWS settings for XBlocks to have filesystem-like storage
Merge pull request #5037 from edx/ammar-ben/bok-choy-shard-3

Split bok-choy tests into 3 shards (merge)
Revert "AWS settings for XBlocks to have filesystem-like storage"
Merge pull request #5040 from edx/revert-5039-pmitros/aws-djpyfs

Revert "AWS settings for XBlocks to have filesystem-like storage"