Add support for Rhel5

Aside from adding supporting for RHEL5 in the module (different handling of udev commandline utilities) I fixed some issues I had been facing:

* fixed deprecation warnings regarding includes_class (changed to contains_class)
* implementaion of a param called config_file_replace (boolean) to protect udev.conf in case replacement is not expected
* git url has been used for github access in .fixtures.yml - this can cause issues with systems behind proxy configurations (while there are workarounds available for git urls as well http urls are usually better especially when push functionality is not required)

The main rspec tests have been corrected, but I am not familiar with the rspec-system tests - these might require investigation)