Guardian command cleanup

Upshift states list as a convenience to user; split on comma or space
as in most other lists
Tell user about invalid argument
Keep pylint happy, eliminate extra spaces

src/gam.py

@@ -2315,11 +2315,14 @@ def doPrintGuardians():
         states = [u'COMPLETE', u'PENDING', u'GUARDIAN_INVITATION_STATE_UNSPECIFIED']
       i += 1
     elif sys.argv[i].lower() == u'states':
-      states = sys.argv[i+1].split(u',')
+      states = sys.argv[i+1].upper().replace(u',', u' ').split()
       i += 2
     elif sys.argv[i].lower() in usergroup_types:
       studentIds = getUsersToModify(entity_type=sys.argv[i], entity=sys.argv[i+1])
       i += 2
+    else:
+      print u'ERROR: %s is not a valid argument for "gam print guardians"' % sys.argv[i]
+      sys.exit(2)
   n = 1
   for studentId in studentIds:
     kwargs = {u'invitedEmailAddress': invitedEmailAddress, u'studentId': studentId}