Filter search results by "module" and "collection"

Filtering by "module" will give the same results as filtering by "page".
Filtering by "collection" will give the same results as filtering by
"book".
Merge pull request #140 from karenc/search-type-module-collection

Filter search results by "module" and "collection"
Update cnxml tests following updates in rhaptos.cnxmlutils
Add test for searching by subject only
Fix search with title and subject
More tests for search
Add filter only tests
Merge pull request #141 from karenc/fix-search-with-subject

Fix search with subject
Merge branch 'master' into limit-only-tests

Conflicts:
	cnxarchive/tests/test_search.py
	cnxarchive/tests/test_views.py