Corrected test module head documentation
Shell core: correction of behaviour

- execute() returns True if the command returned None
- Protection of make_table() against too small columns
- name spaces and commands are stripped and lowered
Added tests for Shell Core
Shell: get_methods_names() is now ignored

The shell does not try to call remote commands, as it is not possible
since the usage of the IOHandler class.
=> the get_methods_names() method is now unecessary
Future.result(): Python 2.6 compatibility

In Python 2.6, threading.Event.wait() returns None instead of the Event
state