Minor: Rename rdiffbackup entrypoint into pbs

setup.py

@@ -72,10 +72,10 @@ setup(name=name,
           'lamp.simple = slapos.recipe.lamp:Simple',
           'logrotate = slapos.recipe.logrotate:Recipe',
           'logrotate.d = slapos.recipe.logrotate:Part',
+          'pbs = slapos.recipe.pbs:Recipe',
           'publish = slapos.recipe.publish:Recipe',
           'publishurl = slapos.recipe.publishurl:Recipe',
           'proactive = slapos.recipe.proactive:Recipe',
-          'rdiffbackup = slapos.recipe.rdiffbackup:Recipe',
           'request = slapos.recipe.request:Recipe',
           'sheepdogtestbed = slapos.recipe.sheepdogtestbed:SheepDogTestBed',
           'softwaretype = slapos.recipe.softwaretype:Recipe',