python-cpopen is needed on jenkins slaves

[Yaniv Bronheim]

Hey,

In the last days cpopen packages was released as part of EPEL and fedora formal repository,
I proposed vdsm patch [1] that uses this package instead of our old method using that code as part of vdsm,

For it to work, please install it over the jenkins slaves.

I set this package as BuildRequires, so without it make rpm for vdsm doesn't work.

[1] http://gerrit.ovirt.org/#/c/20142/

Thanks.