* Adds a script to install dependancies when building the Ubuntu
Mesos image (used in OpenStack infra)
* Fixes Dockerfile to build the Ubuntu Mesos image
(it was missing components to add Heat agent in the image)
* Changes the name of the Mesos Ubunutu image because the Ubuntu
version and Mesos version has changed
* Fixes a broken link in the doc
Change-Id: I35ffd4bd358a62dd7cf0d0e485b531a36b6c262b