[MJ-64] Saved Search

Implements the following:
- SavedSearch, SavedSearchDigest model and migrations
- Helper functions for parsing and validating URLs and RSS feeds
- CRUD views and corresponding ModelForms
- jQuery & AJAX for validating URLs
- Infinite scroll paginated view of individual feeds
- Scheduled emails using Celery & Rabbit
- Custom template tags for user friendly display of certain django fields
- Tests and stuff 

Probably needs some additional work to make it look purtier but all the functionality is pretty much there already.

All tests pass.

Resolves the following tickets:
[MJ-64] saved search - saved search app
[MJ-125] email - schedule process for sending email