add kolla-common shell library to base image

This adds a /opt/kolla/kolla-common.sh to the base image as a place to
put commonly used functions.  The goal is to avoid code duplication
across all the images created from this base image.

Change-Id: Ib670fe369bb8048aa69979b74a984fa4ddaae7d9
Merge "add kolla-common shell library to base image"