[builder] Extend a bit the creator interface

It now take two more argument with default value:
    - action allows to choose what do to with the blendname passed in
      parameter, don't care and add empty (default behaviour), import it
      or just reference it.
    - make_morsable allows to enable or disable the addition of Morse
      logic.

It makes the creator API able to deal more easily with stuff previously
created with Actuator / Sensor.
[builder] Make gripper an ActuatorCreator
[builder] Introduce ArmatureCreator and use it in place of Armature
[builder] Convert PA_10 to ActuatorCreator

Untested
[builder] Kill Sensor / Actuator / Armature