Align usage of test skipping.

There were three different mechanisms for skipping tests in the suite.
For the most part, skipIf was used, so sync to that. Additionally, it
was being used as a decorater in most places, but as a call in a few,
so make it a decorator everywhere. Finally, if it's on the setUp method,
it's not necessary for it to be on any of the individual tests in the class.

Change-Id: I7fbd09a6bc015e698a190b989d0f8641c4adb63e
Clean up a pyflakes error in a comment.

This is a little-bit silly, but it's the last thing. pyflakes parses
python lines that are in docstring comments that are prefaced by >>>.
So, without the import, pyflakes complains about undefined import.

Change-Id: Ibac77367efb07b65b992694b2de19473ec9ef473
Merge "Align usage of test skipping."
Merge "Clean up a pyflakes error in a comment."