Depend on WebOb==1.2.3 to align with other OS projects

Change-Id: Ic1b113a63a9fa44acf98efbe18783f5be5cbeada
Add update support to InstanceGroup

Change-Id: Ie4d554f7440d06d408f71ff1b223d34d50b655bc
Merge "Depend on WebOb==1.2.3 to align with other OS projects"
Merge "Add update support to InstanceGroup"