TODO: add package.xml file.

* Arms have 8 DOF instead of 7 (include last gripper joint)
* include the grippers as a fixed joint

*Previous halfSitting had non-horizontal feet

[urdf] Change talos_small.urdf to use the smaller STL meshes.

* depends on urdfdom>=0.2.9. does not depend on Catkin
* remove package.xml
* add submodule cmake

NOTE: ASSIMP is angry with the header of the bigger STL files like arm_1.stl

*talos_small(without gripper),
*talos_full_collision(loading collision geometry)
*talos_full(loading full mesh geometry)

*make talos_description into current package. remove other sub-packages
*Contains srdf file with feet specificities, halfSitting and disabled collision pairs
*Contains urdf file for loading simpler "collision" geometry in visual models.

*update half-sitting pose to a more dynamically stable one
*remove "Default" disabled collisions with leg_3_link and other common one
*remove other disabled collisions based on a more thorough Moveit sampling

*Defines the half-sitting position
*Defines common kinematic chains
*Disables "always in collision", "never in collision" and "adjacent" collision pairs after sampling of Configuration Space with Moveit.