minor fixes
participation app cleanup + tests
DRY (Don't Repeat Yourself) in custom save and delete methods of participation app
Merge branch 'master' of github.com:codeforeurope/nodeshot into refactoring

Conflicts:
	nodeshot/community/participation/models/__init__.py
	nodeshot/community/participation/models/comment.py
	nodeshot/community/participation/models/rating.py
	nodeshot/community/participation/models/vote.py
	nodeshot/community/participation/utils.py
root endpoint + test
nodeshot.core.api urlpatterns now includes only modules which are listed in INSTALLED_APPS
nodeshot.core.api urlpatterns now includes only modules which are listed in INSTALLED_APPS