add spec/acceptance coverage for passenger module

add basic spec/acceptance tests for passenger module; these verify a
default installation as well as passing in module loading parameters.
new tests revealed undocumented Redhat dependencies on 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.

also, documented new apache::mod::passenger parameters (originatinig
with apache::mod) in README.passenger.md