Fix _start_build

- Add a test for start_build
- pass the context into image.save()
- use Popen instead of check_output (to support py2.6)

Change-Id: I8d63b1034f623ffa60906946ce7889d68a7ebbb6
Connect db and api for 'Operation'

Change-Id: I8b91138c5f81ffd58a23a68ba9be331c650328dc
Add some missing @exception.wrap_controller_exception

Change-Id: I54af751f269713a9608936089b0ba6061fca307b
Merge "Fix _start_build"
Merge "Connect db and api for 'Operation'"
Merge "Add some missing @exception.wrap_controller_exception"