refs #7227 - configure Brightbox Ruby NG PPA for Ubuntu 12.04 (precise)
refs #7227 - install passenger-common1.9.1 on Ubuntu 12.04

Add passenger_ruby_package parameter to control additional package resource
for installing the Passenger libs for the version of Ruby that will be used
to run Foreman.  Begins to replace passenger_scl, which will be superseded by
this param and passenger_ruby.
refs #7227 - set PassengerRuby to ruby1.9.1 on Ubuntu 12.04

Explicitly set PassengerRuby from the passenger_ruby parameter and set it to
ruby1.9.1 on Ubuntu 12.04 to ensure Passenger runs under the intended version
if the system-wide default is changed.

Deprecates the passenger_scl parameter, which has been split into the
passenger_ruby and passenger_ruby_package parameters for more control.

Clarify the support policy which has been followed anyway, and begin to
document how to use N-1 support.