summary.py: Do not generate result summary pages for skips

A status of 'skip' does not make for very interesting reading, and not
generating a status page for it produces a decent increase in
performance, about 1 second off for a quick.tests test result.
HTML summary: Provides means to exclude generating test result files

This provides a switch and method for excluding the generation of the
test result HTML files (those that live under <testrun name>/). This
allows the user to trade some verbosity in the results for a significant
increase in generation speed. A run of quick.tests with all options
enabled takes ~5.5 seconds, with just pass and skip disabled it only
takes ~2.5 seconds. This only becomes more significant as more testsruns
are added the HTML page.
Summary.py: Convert self.tests into default dict

This is actually a really good use of lambda, and allows us to drop a
lot of try except blocks
summary.py: count the total number of tests passed, failed, etc

This is Useful for generating text files, but it generally seems like a
useful bit of information to have, for summaries.
summary.py: Add generateText() method to NewSummary.py

This will be used to replace the existing piglit-summary.py code, and
convert it to use the new summary backend.
piglit-summary.py: convert from getopt to argparse

argparse requires less code, and is much easier to read and maintain.
piglit-summary.py: Convert to using new summary for generation

This changes the output to actually use the NewSummary class.
This produces no real change in speed, despite the fact that the new
method is compiled while the old method is not, most likely this is
overhead from the constructor for the NewSummary class