Add basic dependency handling to PackageTrack and PackagerGroup. PackageTrack now extracts dependency information from the debian/control file and PackagerGroup sorts the tracks based on this information so that packages on which other packages in the group depend on are built first and their newly built binaries are installed added to the pbuilder instance. Also add some test cases.

.*\.pyc$
.*~$
.*\.cfg$
test/temp/.*$