Begin to setup some router integration tests.

More needs to be done here, but this finally starts to add some tests on
the full stack router behavior, so we can test how nginx and varnish
integrate with the gatekeeper.
Print out stderr if process exists abnormally to help debugging.
Add tests around header sizes and limitations.

These are just the defaults in the entire stack, and we could certainly
tweak these if needs be, I just wanted a reference point to know what
our current limits are.
Bump gatekeeper.
Merge branch 'master' into gsa

Conflicts:
	gatekeeper