Add git to Docker Image

[ikegentz]

git should be included in this Docker image. Since the purpose of the image is to run Ansible playbooks that will naturally reside in a git repository, it only makes sense to include git itself for the purpose of switching between branches.

While you can, and should, keep the repository in question cloned into a Docker volume outside of the container, you still need git inside the container to switch to development branches, since everything will not always be in the master branch