Regression: git is required to build from source on ubuntu

- this change fixes a regression of bug/1481560
- this change re-adds git to the openstack base image
  when building images from source on ubuntu.
- removed explicit git install from kolla-ansible

Closes-Bug: #1496561
Change-Id: Ia8a125e40bc6510af6d44c5317647be7ce27b0d6

docker/kolla-ansible/Dockerfile.j2

@@ -4,7 +4,6 @@ MAINTAINER Kolla Project (https://launchpad.net/kolla)
 {% if base_distro in ['centos', 'fedora', 'oraclelinux', 'rhel'] %}
 
 RUN yum -y install \
-        git \
         gcc \
         libffi-devel \
         libxml2-devel \
@@ -16,11 +15,6 @@ RUN yum -y install \
 
 RUN pip install -U pip wheel
 
-{% elif base_distro in ['ubuntu', 'debian'] %}
-
-RUN apt-get install -y --no-install-recommends git \
-    && apt-get clean
-
 {% endif %}
 
 RUN pip --no-cache-dir install shade

docker/openstack-base/Dockerfile.j2

@@ -15,6 +15,7 @@ RUN apt-get install -y --no-install-recommends \
         libffi-dev \
         libyaml-dev \
         pkg-config \
+        git \
     && apt-get clean
 
     {% endif %}