This adds a weston-test-runner for the weston test extension and
some weston test client helper methods.
Converted keyboard-test to use the new test interface, runner,
and helper methods.
Fixes https://bugs.freedesktop.org/show_bug.cgi?id=56822
Signed-off-by: U. Artie Eoff <ullysses.a.eoff@intel.com>