enable overriding mod-level parameters for apache::mod::passenger

apache::mod::passenger didn't accept/pass (optional) mod parameters
through to apache::mod, so only auto-generated module parameters were
used.  Without this option apache::mod::passenger could not be used in
conjunction with passenger modules beyond those generated by OS package
system (in particular, modules compiled via
passenger-install-apache2-module, which use differing paths).  This
commit enables passing in all parameters used with "apache::mod",
documented in the passenger README

includes basic spec/acceptance tests; verifying a default installation
as well as passing in module loading parameters.

new tests revealed undocumented Redhat dependencies on a passenger-
specific repository as well as the EPEL repository; as a first step
these dependencies are being manually resolved during setup for the
acceptance testing suite.