Bug 989137 - Part 8: Prevent unknown experiments from being installed; r=Unfocused

The experiments service insists on being in control of experiments.
Before, it wasn't being as assertive as it needed to be: other browser
components could install experiments behind its back. This patch
reasserts the experiments service as king of experiments add-on
management.

--HG--
extra : rebase_source : 6d9b94f91865ef3c6929bc34cd3e7bb57e112d14
Bug 989137 - Part 9: Ensure add-ons are enabled when they should be; r=Unfocused, r=gfritzsche

Experiment add-ons are disabled by default in the Addon Manager. This
patch will manually enable them if necessary.

--HG--
extra : rebase_source : be3d7c7489fa851dc421b5bae05978fa8ba17539
Bug 989137 - Part 10: Add a testing-only JSM for common AddonManager operations; r=Unfocused, r=gfritzsche

There is a lot of boilerplate testing code that performs common
AddonManager operations. Some common operations used for testing
Experiments have been refactored into a testing-only JSM that lives as
part of the Add-ons Manager.

--HG--
extra : rebase_source : 7b595e2a93637a1b2746e0182fbbe897c93fb6d9