System Image Upgrade Testing

System-image and ubuntu-download-manager have fairly extensive unit testsuite with pretty good code coverage.
When package builds it runs the full test suite and a subset of it during autopkgtest

But it never goes outside of localhost and there is no extensive integration tests. More particularly, there is no end to end test against the real server and the real UI that the mocks are not able to catch.

https://bugs.launchpad.net/bugs/1277589 is an example of bug critical bug that escaped current testing.

The purpose of this project is to implement the tests described in [1] and automate them in CI.

= References =
[1] https://wiki.ubuntu.com/Process/Merges/TestPlan/ubuntu-system-image
[2] https://docs.google.com/a/canonical.com/spreadsheet/ccc?key=0AhmCwOxnFq5LdGt0bDJlNmoyZ2ZCU3RIRDR0RzhxV3c&usp=drive_web#gid=0
[3] https://wiki.ubuntu.com/SoftwareUpdates#Phone
[4] https://wiki.ubuntu.com/DownloadService/
[5] http://bazaar.launchpad.net/~ubuntuone-hackers/ubuntu-download-manager/trunk/view/head:/docs/DownloadStateMachine.dia
[6] https://code.launchpad.net/~diegosarmentero/ubuntu-system-settings/click-updates/+merge/208567

Work items:
[chris.gagnon] Implement proxy for system-settings to make it testable by Autopilot: DONE
[chris.gagnon] Implement upgrade test case 1 - "n-1 to n": INPROGRESS
[chris.gagnon] Implement upgrade test case 2 - "n-2 to n": INPROGRESS
[chris.gagnon] (with CI) deploy test cases 1 and 2 in CI: TODO