Fix Debian packaging Dockerfile and docs.

packaging/debian/Dockerfile

@@ -7,7 +7,11 @@ RUN apt-get update && apt-get install -y \
     devscripts \
     make \
     pbuilder \
-    python-setuptools
+    python-jinja2 \
+    python-setuptools \
+    python-yaml \
+    && \
+    apt-get clean
 
 VOLUME /ansible
 WORKDIR /ansible

packaging/debian/README.md

@@ -9,7 +9,6 @@ __Note__: You must run this target as root or set `PBUILDER_BIN='sudo pbuilder'`
 apt-get install asciidoc cdbs debootstrap devscripts make pbuilder python-setuptools
 git clone https://github.com/ansible/ansible.git
 cd ansible
-git submodule update --init
 DEB_DIST='xenial trusty precise' make deb
 ```
 
@@ -18,7 +17,6 @@ Building in Docker:
 ```
 git clone https://github.com/ansible/ansible.git
 cd ansible
-git submodule update --init
 docker build -t ansible-deb-builder -f packaging/debian/Dockerfile .
 docker run --privileged -e DEB_DIST='trusty' -v $(pwd):/ansible ansible-deb-builder
 ```