Move storage of user filters into real datastore layer; now have to mock it out in the REST-level tests

Initial trivial implementation of an actual 'Filtering' object; move storage of user filters into there

Don't pass the HS to serialize_event just so that it can get the current time.

HS and getting a clock from it and calling time_msec on the clock.
Remove the serialize_event method from the HS since it is no longer
needed.

Initial minimal attempt at /user/:user_id/filter API - in-memory storage, no actual filter implementation

Extract the client v1 base RestServlet to a separate class

Remove parse id from hs

Merge rest servlets into the client json resource object

Rename MockedDatastoreTestCase to MockedDatastorePresenceTestCase since it is still presence-specific

shareable

Move client v1 api rest servlets into a "client/v1" directory