Wrap tidepool backend code into api service

- Wrap both `tidepoolplatform` (to be deprecated) and
  `tidepool-platform-client` (new separate library) into `core/api`
- Have `tidepoolplatform` return an object rather than "patch" an
  existing one (that's really used for mocks)
- Introduce `tidepool-platform-client` via Bower
- Merge `core/auth` into `core/api` under `api.user`
Add fetch patients for user

Use tidepool-platform-client to implement `api.patient.getAll()`.
Update to latest platform client API
Merge pull request #33 from tidepool-org/platform-client

Platform client