Fix backward compatibility of `manage_redhat_firewall` parameter

Prior to this commit, the deprecated `manage_redhat_firewall` param
was not actually backward compatible because there were several
cases where we couldn't tell the difference between the user
explicitly specifying `false` for that parameter as opposed to
not specifying it at all.  This commit is a bit ugly because it
sets some defaults to `undef` in order to allow us to tell the
difference between the two cases, but it should resolve backwards
compatibility issues.
Update Modulefile and CHANGELOG for 1.1.4 release