(PDB-465) Remove Ubuntu 14.04 trust support for master

Since we pin against 3.5.1 for Puppet, we need to wait until Puppet does
a trusty release before this will work.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #944 from kbarber/ticket/master/pdb-465-remove-ubuntu-1404-for-master

(PDB-465) Remove Ubuntu 14.04 trust support for master