(MCOP-244) Checkupdates lacks zypper (SLES) knowledge

This allows checkupdates to work with zypper on SLES systems.  Tested on
SLES 11SP2 and SLES 11SP3.
Merge pull request #13 from atopian/master

(MCOP-244) Checkupdates lacks zypper (SLES) knowledge