Add support of upgrade gerrit to v2.5

Add gerrit.war and scripts of handling the upgrading.

Change-Id: Ie9b18909a8f1c2739c30078ef190ea9db5b0e18b
Extract auto-review config to manifest

Allowing multiple team to monitor on same projects.
Also open hooks.tgz to plain src.

Change-Id: Ia9c1b2ec05b9f7bdbf30f62bafbd2651f2a04a47