Modify the checks to see if bz summary contain 'Upgrade'

Before check was to see if bz summary starts with 'Upgrade',
now it only check if bz summary has 'Upgrade' in it.

Reason is because the way summary is now created:

'RHEL6 RPMs: Upgrade <package> to <version>' instead of
'Upgrade <package> to <version>'
Merge pull request #55 from thescouser89/summary_change

Modify the checks to see if bz summary contain 'Upgrade'