Beginnings of a provider for Azure Table Storage

This code uses the [Azure Storage Client Library](http://msdn.microsoft.com/en-us/library/azure/dn261237.aspx) to provide data for EF.

Completed tasks:
- [x] Can create a DbContext that uses ATS.
- [x] DbSets can create, update, and delete entities.

Important TODOS:
- [ ] Optimize queries (they pull the entire table into memory)
- [ ] Navigation properites/foreign keys
- [ ] Error handling, esp. for concurrency issues

The functional tests require configuration against a real Storage account. See instructions in that project's README for details on setting up the connection string for the tests.