Use of puppetlabs-apache in the installer

Happy new year everyone!

As some of you may know, I've been working on using puppetlabs-apache
instead of theforeman-apache as our apache module to better integrate
into existing environments.

Now I've reworked my V1 patches1[3] and created v2 ones. Initial
testing on CentOS 6.4 works with default parameters, so now it's time to
test more configurations. Any reviews are very welcome.

Something I'm still very unsure of is the passenger_root which is
currently set statically when scl_prefix is given. I believe this should
be fixed upstream and does not belong in our module.

Some simplifications that make the conversion and testing easier.

Includes #124.

I also drop the passenger_max_pool parameter silently. The proper fix
would be to add passenger parameters to apache::vhost upstream so it can
be set per vhost.

Work in progress. Obviously the foreman and puppet URLs shouldn't be
changed in the when the other PRs have been merged.

My aim is to get his in for Foreman 1.4, which I believe is targetted
for February.