reject updates to deleted cases and change tests to reflect that

also rearranged the precedence of case doc checks to check domains before anything else
remove/add forms from case history when they are archived/unarchived

+ tests.

a few other little things got bundled into this. oops.
Merge pull request #91 from dimagi/case-deleted

reject updates to deleted cases and change tests to reflect that
handle and test the 'deleted' case
bump couchforms
Merge pull request #92 from dimagi/form-archive-support

remove/add forms from case history when they are archived/unarchived
Add parent case lookup utility
Remove utility class in favor of memoization
Merge pull request #93 from dimagi/parent-case-lookup

Add parent case lookup utility
fix case wrapping

loading settings.CASE_WRAPPER at module import caused a circular import.
Lesson: always use failhard=True with to_function to avoid masking
errors when things get changed.
Merge pull request #94 from dimagi/fix-case-wrapping

fix case wrapping
Merge branch 'master' into case_multimedia

Conflicts:
	casexml/apps/case/models.py