Bug fix - Find latest RHEL5 Kickstart path

Changed the behaviour how to find latest kickstart tree path, it affects mainly RHEL5.
With the introduction of RHEL5.7 the name of the kickstart tree directory changed from "ks-rhel-x86_64-server-5-u6" to "ks-rhel-x86_64-server-5-5.7".
Bug fix - common functions are sourced too early

The common functions are sourced too early. This leads that (KSPREFIX, AKPREFIX, CCPREFIX and CHANNEL_Prefix) are set wrong, when you like to Clone RHEL5 and not the default RHEL6.
Merge pull request #3 from ggruner/master

Bug fix - Find the latest RHEL5 Kickstart tree path