expose --listen* command line arguments in RPM init script

The current RPM init script does not allow changing the addresses Jenkins listens on. This patch extends the current sysconfig variables to do so. Better still would be for Jenkins to listen on localhost by default, but that's beyond the scope of this patch.

This is tangentially related to JENKINS-5188. I believe this issue can be closed as it's been fixed for some time and documented at:

https://wiki.jenkins-ci.org/display/JENKINS/Starting+and+Accessing+Jenkins#StartingandAccessingJenkins-CommandLineParameters