(PDB-597) Add trusty build default

This includes trusty (Ubuntu 14.04) in our builds.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #967 from kbarber/ticket/stable/pdb-597-trusty-support

(PDB-597) Add trusty build default
sbin_dir logic to Rakefile

Archlinux uses /usr/bin instead of /usr/sbin
Merge pull request #971 from aboe76/stable

Add sbin_dir logic to Rakefile
(PDB-686) Add warning about PDB-686 to release notes

This adds a warning about PDB-686 to the release notes so users know how to
work-around it.

This also cleans up the linking in our current release notes, and removes the
warning about Puppet 3.4.x, because we pin against 3.5.1 and greater anyway.

Signed-off-by: Ken Barber <ken@bob.sh>
Merge pull request #973 from kbarber/ticket/stable/pdb-686-ubuntu-1204-ruby-193-warnings

(PDB 686) Add warning about PDB-686 to release notes
Merge branch 'stable'

* stable:
  (PDB-686) Add warning about PDB-686 to release notes
  sbin_dir logic to Rakefile
  (PDB-597) Add trusty build default