Docker has an undeclared dependency on apparmor for Ubuntu Trusty,
preventing the daemon from running and causing any -src jobs for IPA to
fail when using docker to build the package.

This should unbreak the IPA gate.

This is not a direct cherry-pick, as ironic in Mitaka uses a devstack
plugin, while ironic in Liberty uses devstack directly. This is,
however, a direct port from ironic's master branch. The commit there is
3a6a8ec98e56816c4671648d11716d71adc366b0.

Change-Id: I4c19c96d2d5cd8accb9ed8df6241fc9f0c229e0e
Co-Authored-By: Jay Faulkner <jay@jvf.cc>