Rearrange the imports to meet the style guide

This also includes `from __future__ import absolute_import`
in every file so that the imports are consistent in Python 2 and 3.
The Python 2 tests fail without this.

tests/test_resolver/test_mbs.py

@@ -1,13 +1,15 @@
 # -*- coding: utf-8 -*-
 # SPDX-License-Identifier: MIT
+from __future__ import absolute_import
+
 from mock import patch, PropertyMock, Mock, call
 
 from module_build_service import app, conf
 from module_build_service.builder.MockModuleBuilder import load_local_builds
+import module_build_service.common.models
 from module_build_service.common.utils import load_mmd, mmd_to_str
 import module_build_service.resolver as mbs_resolver
 from module_build_service.scheduler.db_session import db_session
-import module_build_service.common.models
 import tests