do nothing by default and prevent traceback

If not given the function, we get:

aceback (most recent call last):
  File "/home/users/nico/p/cdist/core/bin/cdist", line 243, in <module>
    commandline()
  File "/home/users/nico/p/cdist/core/bin/cdist", line 107, in commandline
    args.func(args)
AttributeError: 'Namespace' object has no attribute 'func'

Signed-off-by: Nico Schottelius <nico@brief.schottelius.org>

bin/cdist

@@ -39,12 +39,15 @@ def commandline():
         help='Set log level to info, be more verbose',
         action='store_true', default=False)
 
-    # Main subcommand parser
+    # Main parser
     parser['main'] = argparse.ArgumentParser(description='cdist ' + cdist.VERSION,
         parents=[parser['loglevel']])
     parser['main'].add_argument('-V', '--version',
         help='Show version', action='version',
         version='%(prog)s ' + cdist.VERSION)
+    #parser['main'].set_defaults(func=commandline_main)
+
+    # Subcommand shell
     parser['sub'] = parser['main'].add_subparsers(title="Commands")
 
     # Banner
@@ -103,6 +106,9 @@ def commandline():
     log.debug(args)
     args.func(args)
 
+def commandline_main(args):
+    pass
+
 def config(args):
     configinstall(args, mode=cdist.config.Config)