The mongo integration was using a very old package. It's using
a new namespace now. Upgrade and adjust all call points
Removes labix.org/v2/mgo
Introduces gopkg.in/mgo.v2 from branch v2 with revision
3f83fa5005286a7fe593b055f0d7771a7dce4655
Change-Id: I2784fca941998460f58e0ac8d3d51286401590b5