Add missing license file

package.xml: Add catkin/ament_cmake runtime dependency for packaging

Required by REP-136

Reverted back removation of base_inertia + added tiny inertia in base

Use pinocchio model for internal functions

With this approach, we could reuse this method without the needed of
using RobotWrapper.

update solo12

[README] document ROS_PACKAGE_PATH use

from https://github.com/open-dynamic-robot-initiative/open_robot_actuator_hardware/tree/master/mechanics/quadruped_robot_8dof_v1/stl_files_for_visualization

[CMake] pinocchio required only for tests, fix #22

Fix package paths in URDFs - resolve issues 9,19