Prevent unstable test result when run in specific time

If run test between 23:00 to 1:00 in locali time, result is unstable.
This patch fixes it.
Fix watchdog leaks in GerritConnection.

Change-Id: I4374d223d968f383aa414160bc8c62f28b41cecd
Merge pull request #99 from rinrinne/fulltime-testable

Prevent unstable test result when run in specific time
Merge pull request #100 from mathieu-wang/watchdog-leaks

Fix watchdog leaks in GerritConnection.