Port 8080 is a bad choice and bumps into puppetdb
Add a type and provider to manage apt keys.

This commits introduces:
 * The apt_key type;
 * The apt_key provider;
 * Unit tests for the type;
 * Beaker/acceptance tests for the type/provider.

The idea behind apt_key is that apt::key will simply become a wrapper
that uses apt_key. Being a native type/provider apt_key is a lot less
error prone than the current exec behaviour of apt::key and adds a few
nice bonuses like inventory capabilities for mcollective users.
Travis: Remove 3.0, add newer 3.x releases.

3.0 is just broken in tests, something is wrong with the module loading
rendering tests completely useless.

Start testing on Puppet 3.3 and 3.4.