Merge pull request #17 from ktf/V00-21-XX

Fix building cmssw-patch releases with new scheduler.
Updated to include all fixes in V00-22-XX.
Merge pull request #18 from ktf/V00-21-XX

Updated to include all fixes in V00-22-XX.
Add sparse checkout like behavior for git source fetching.
Merge branch 'V00-21-XX' into V00-22-XX
Merge branch 'V00-22-XX' of github.com:cms-sw/pkgtools into V00-22-XX