oversize on f18 again. ;)

[Kevin Fenzi]

https://bugzilla.redhat.com/show_bug.cgi?id=853590

Some options: 

- nuke icedtea-web (this saves 100MB or so, but means people won't be
  able to test java in the live instance). 

- seahorse - 7mb

- Longer term: split perl deps out of exo and see if we can remove
  perl? lm_sensors also needs perl, so we would have to drop
  xfce4-sensors-plugin, but I think it's worth it. That could save us a
  ton of room down the road. This dep is due exo-compose-mail-1 helper
  being a perl script. 

- drop one of firefox or midori. ;) 

- We really only need a bit of room at this point, so other smaller
  suggestions?

kevin