UIUC Create This! Day 2013-03-28

Changes to the server project:

- Add an external_id to the Spot model to facilitate syncing with an external database. This is meant to hold the ID for that spot in the external system. The only URL that changed was for /api/v1/spot/(id) to add "external:id"

- Add hooks for additional search filtering to views/search.py, with the associated org_filters module to hold them. This allows us to modify the DB query and/or the resultant Spot set to filter based on our own criteria.

- Move some UW spot type code into a org_filters/uw_search.py module.

- Allow an open_anytime search parameter in order to ignore the available hours, if requested.

Hopefully I'll be able to organize the changes on the web front end soon.