Make foreman integration optional

Instead of including foreman::params, the values are copied. That means 
foreman::params no longer needs to be included.

The next use of foreman is in puppet::server::config where it sets up 
reporting and ENC. This is wrapped in a new boolean $server_foreman. The user
will still need to take care of clearing $server_reports and
$server_external_nodes.

Fixes #154
We could also drop ```server_foreman_ssl_*``` and reuse ```puppet::server::ssl_*```. I've got a patch ready that does that and would simplify the module.

Another path is also to first get the packaging done so ```server_puppet_basedir``` is no longer needed either (since it's in packages). Then the integration could also be greatly simplified and fully pulled away from ```foreman::puppetmaster``` and into ```puppet::server::foreman```.