[Piglit] V2 Finish replacing summary

[Dylan Baker]

This series finishes replacing the old Summary class with the NewSummary
That was added for the new HTML backend.

Patches 1 and 4 are groundwork changes that should be transparent to end
users
Patches 2 and 3 Do a little bit of cleanup for HTML summary generation,
namely they stop generating pages when there is no content.
Patches 5-9 Convert piglit-summary.py to use the NewSummary class
Patches 10-11 Change the behavior of piglit-summary-juint.py. These changes
follow discussion with Jose and constitute the majority of the V2 changes
Patch 12 renames the NewSummary class to just Summary