Ensure apt-get installs do not prompt user input

Set DEBIAN_FRONTEND to noninteractive and add dpkg options to ensure
apt-get installs do not prompt for input and cause the stack-create to
fail.

Closes-Bug: #1245899

Change-Id: I294783fb565b854143bc8a5d15834d8d88ad1a70
Pin version of pbr in Cloud Server resource

This is a temporary workaround for a bug in pbr 0.5.22 which causes
the heat-cfntools install to fail.  More details at:
https://bugs.launchpad.net/ubuntu/+source/python-pbr/+bug/1245676

Closes-Bug: #1245896

Change-Id: I9c0bc4d699af6782447efdd84bdde732664c8a27