Don't walk suites where all their tests have been filtered out.
Rename reporter methods.
Add a JUnit XML reporter.
Allow format for PhantomJS tests to be specified on the command line.
Change precedence of envvars vs argv for enabling TAP output, allow format to be set by autorun(), and enable TAP envvar detection for Rhino.
Allow the --test and --format options to be set through equivalent envvars, since we can access those easier than argv on Rhino.