[C++][Python][Parser Geom] Parse automatically the ROS_PACKAGE_PATH environment variable if not clue is given by the user to where to search for meshes. Change the meshRootDir argument to a vector of strings (package directories). Updated Python consequently

Improve doc of Model+Data and add python bindings in Travis

Add CCRBA algorithm

Add ABA algorithm

Inertia.From{Ellipsoid,Cylinder,Box}

Rework center of mass algo + Python API

Use the name for all the algo related to centerOfMass computations. All
of them now return the center of mass position of the whole rigid body
system. Add also to compute only the position and velocity of the CoM

Add missing namespace

Rework SRDF parsing + correct GeometryModel parsing from URDF

The geometries are now loaded by reading again the URDF file. From now,
one has to build a model first from a URDF file, then to load the
geometries according to this model.

This reference is mandatory, just because a GeometryModel is linked to
a kinematic Model

Handle SRDF file parsing for activation of collision pairs