cleaning up several programlistings

  * removing newlines at start and end
  * setting/adding correct language
  * converting from programlistings to screens

backport: havana

Cherry-Picked: https://review.openstack.org/#/c/53607/
Change-Id: Idceefccf057abe43433a2ddd52743f8b7b960646
Add Missing Newline In OVS Plugin Setup

There is a missing newline between two commands in step 3
of the OVS plugin setup instructions.  This fixes that.

Cherry-Picked from: https://review.openstack.org/#/c/53383/
Change-Id: Ic990eb99ae3f5c8159ae16296f73bd472c6bbddf
Fixes: bug #1243734
backport: havana
Merge "cleaning up several programlistings" into stable/havana
Merge "Add Missing Newline In OVS Plugin Setup" into stable/havana