Updating cmd/manage.py get_arg_string() argument parser

Looks like get_arg_string() would improperly chop off the first two characters
of an argument that was passed in with one dash (-example).

Change-Id: I4409d3a2a3545e7160c0e666a864f8630bc141f1

designate/cmd/manage.py

@@ -84,7 +84,7 @@ def get_arg_string(args):
             # This is long optional arg
             arg = args[2:]
         else:
-            arg = args[3:]
+            arg = args[1:]
     else:
         arg = args