Bug 993136 - Fix TestSyncConfiguration.
Bug 993136 - Fix TestSyncConfiguration. r=mcomella
Bug 993134 - Part 1: Make getApplicationContext return getTargetContext.

I was finding that repeated instrumentation-test runs were returning a
null application context, indicating a race between test start-up and
target instantiation.  This works well for me on two test devices.
Bug 993134 - Part 2: Extract AndroidSyncTestCaseWithAccounts.
Bug 993134 - Part 3: Use AndroidSyncTestCaseWithAccounts to make fxa.TestAccountPickler when accounts exist.
Bug 993134 - Part 4: Make fxa.TestAccountPickler robust.

This tested extracting data from an AndroidFxAccount before, and another
after, backed by different Android Accounts.  Unfortunately, one Account
replaced the other, but had the same name, leading to a race
condition (between reading and deleting the first account).  To address
this, we extract all the data before deleting, and then compare it to
the data from the newly pickled account.
Bug 993134 - Part 5: Work around Android intermittent issue.
Bug 993134 - Make TestAccountPickler tolerate multiple accounts. r=mcomella
Bug 1019793 - Don't create storage in TestHealthReportPruneService.

Creating real storage requires a valid Context, and in this test, we
only have MockContext.
Bug 1019793 - Always upload in TestHealthReportUploadService.
Bug 1019793 - Avoid UnsupportedOperationException in TestHealthReportPruneService. r=mcomella