Use ZUUL_URL in ggp

Makes ggp more generally useful and needed to support multiple
Zuul mergers.

Change-Id: I3c6989f6a710bc124f55aed810be0d4888c67727
Ensure a recent(48h) check result

Change-Id: I32c19cf487e1c1be3e6ca3b5ce3045f80a38aa45
Merge "Use ZUUL_URL in ggp"
Merge "Ensure a recent(48h) check result"