Implement logs model using Elasticsearch

- Implement logs model using Elasticsearch with tests
- Implement transition model using both elasticsearch and database model
- Add LOGS_MODEL configuration to choose which to use.

Co-authored-by: Sida Chen <sidchen@redhat.com>
Co-authored-by: Kenny Lee Sin Cheong <kenny.lee@redhat.com>

app.py

@@ -21,6 +21,7 @@ from avatars.avatars import Avatar
 from buildman.manager.buildcanceller import BuildCanceller
 from data import database
 from data import model
+from data import logs_model
 from data.archivedlogs import LogArchive
 from data.billing import Billing
 from data.buildlogs import BuildLogs
@@ -267,5 +268,6 @@ def load_user(user_uuid):
   logger.debug('User loader loading deferred user with uuid: %s', user_uuid)
   return LoginWrappedDBUser(user_uuid)
 
+logs_model.configure(app.config)
 
 get_app_url = partial(get_app_url, app.config)