Some functional tests for static large objects

There's some sort-of-hacky code in there to detect SLO support in
order to skip tests when SLO is off so that the functests won't fail
on older clusters.

Change-Id: I6ad5974a0db7213747b0f4497d08ffc706d3f220
Fix bug in obj updater run_once().

The "not" in front of the ismount() call got accidentally dropped in a
recent change.  This patch adds it back along with a few more tests.

Note that this bug only showed up on an SAIO during probe tests because
I used actually-mounted (virtual) "disks".  So keep that in mind when
building SAIOs for development/testing.

Change-Id: Ia193f3c4b73203605954036863575c22ddab6b03
Add HTML reporting for test branch coverage.

When including branch coverage results, also generate HTML reports into
a "cover" subdirectory under the directory in which .unittests resides
(i.e. known location at the top of the swift tree).

Change-Id: I493d74f38755f7bf0d7043052585efb27840b238
Merge "Fix bug in obj updater run_once()."
Merge "Add HTML reporting for test branch coverage."
Merge "Some functional tests for static large objects"