jenkins-slave: add python-inotify, python-ply

    - python-inotify is required by create vdsm job
    - python-ply is required by rhevm-cli rpm
    - currently enabled on both fedora & epel,
      we should ensure epel repo is available on centos

Change-Id: I9391cf956b26ceea41fa8e1305bf63bd1ebc311e
Signed-off-by: Eyal Edri <eedri@redhat.com>