[#6828] Changes related to activitystream refactor

- Activities are proper objects now, not dicts
- Specify Ming as default storage driver in setup.py
- Configure activitystream for tests

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#4452] Add activitystream to ensure_index command

Signed-off-by: Tim Van Steenburgh <tvansteenburgh@gmail.com>
[#4452] Bumped ActivityStream version and fixed HTML5 validation error

Signed-off-by: Cory Johns <cjohns@slashdotmedia.com>