This PS adds validation logic recently implemented in
armada.utils.validate [0] for validating documents and
Armada-generated Manifests to the Test and Tests controller classes.
Also refactors some exception handling for both controller classes to
better bubble up the appropriate exception.
Finally unit tests have been added for the Armada Test controller
to verify above changes work.
[0] https://review.gerrithub.io/#/c/378700/
Change-Id: I01f73c1778bf7c2e38032d5fddabd327c013edbb
e4a4d2ea68