Adding ovirt-node requirements

Only centos 7 and fc20 are supported right now, will test and add the others
later.

Had to separate some packages into their own classes so they could be included
multiple times for different slave profiles, better ideas are welcome.

Added also a fix to jnlp class

Change-Id: I49ec48524b9a8b364264028ef3a9dd9e453aa0e7
Signed-off-by: David Caro <dcaroest@redhat.com>