robot_model->njoints has the kinematic tree

Conflicts:
	CMakeLists.txt
	cmake
	include/dynamic_graph_bridge/sot_loader.hh
	package.xml
	src/sot_loader.cpp

Add proper dependence to the SoT packages.

sot_laoder: calls the real time control loop after initializeRosNode.

with filling sensor, control computation and sending control.

Conflicts:
	CMakeLists.txt
	package.xml
	src/converter.hh
	src/geometric_simu.cpp

    CMP0037 forbid to use some target with a special name.
    The current SoT way of binding python create a wrap.py file
    which may blow up with cmake one day of the other.
    For the moment we just change the cmake policy level.

Integrate bug fixed in robotpkg.

A sot plugin should be installed in lib/plugin.