Added tests for the iPOPO waiting list

Corrected the bundle accordingly
Added tests for iPOPO handlers and corrected bugs

- decorators must use set_handler_default instead of get_handler
  => avoids the factory_details method to create empty configurations
     for unused handlers
- components are not considered as waiting for a handler once they
  have been instantiate and until one of their handlers goes away
Renamed "tests_field_callbacks" to "test_..."