tests: drop mongo database before each test run

Change the TestCase base class so it handles dropping the mongo
database before each test run. Since almost all tests will be interacting
with the database it makes sense to handle that at the base level.
blocks/form: add initial form block type with basic field support
couple of fixes around testing blocks
Merge branch 'block-render-implementation' of github.com:damoxc/cms_prototype into damoxc-block-render-implementation

Conflicts:
	cms_prototype/models/table.py
	cms_prototype/tests/test_view_block.py
	cms_prototype/views/block.py
fixed table rendering