Remove unused library load
Check for /var/cfengine/design-center/sketches as default install source

If the lookup for an install source based on the current directory
fails, fail back to /var/cfengine/design-center/sketches/ if it exists.
Merge pull request #436 from zzamboni/fix/default_installsource

Check for /var/cfengine/design-center/sketches as default install source.
DCAPI/Sketch.pm: include location in describe option