Initial commit of RHEL/CentOS compatible RPM SPEC file

Hi Bostjan,

This is my initial attempt at an RHEL/CentOS spec file.  I noticed that the SLES spec in your repo seems based around building from a git checkout, where mine is more based on an official release tarball.

I'm not exactly sure what you're looking for, so I just kept this as simple as possible.  I tested building, installing, and uninstalling on CentOS 7 and can confirm all work, including enabling/disabling on install/uninstall as you requested.

Let me know if there's anything else I can do to help.

Thanks,

Jeremy