sos: enabling additional plugins for sos >= 3

SOS plugins have been refactored between sos 2 and sos 3,
enabling additional plugins for sos > 3

https://bugzilla.redhat.com/1174155

Change-Id: I61c2c5e9a7d5989df75838de503d17390b4d7186
Signed-off-by: Simone Tiraboschi <stirabos@redhat.com>