minor fixes

Change-Id: I4be15d264e402be000811dffc1b28a2bc93ab297
Reviewed-on: https://forge.frm2.tum.de/review/18941
Tested-by: JenkinsCodeReview <bjoern_pedersen@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>

secop/protocol/dispatcher.py

@@ -192,7 +192,7 @@ class Dispatcher(object):
         if moduleobj is None:
             raise NoSuchModuleError(module=modulename)
 
-        cmdspec = moduleobj.commands.get(command, None)
+        cmdspec = moduleobj.accessibles.get(command, None)
         if cmdspec is None:
             raise NoSuchCommandError(module=modulename, command=command)
         if len(cmdspec.datatype.argtypes) != len(arguments):