fix lwa4d urdf - joint orientation according to convention

[fmessmer]

• fixed motor orientation with Schunk MTS

  • adjusted joint orientation in URDF
  • fix orientation in meshes

  Now both hardware and software (motors and urdf) use the convention that +z-axis points towards the next joint!

[ipa-nhg]

This pull request should be tested on a cob3, or at least communicate the cob3 developers that they should not update their repository before check with MTS the motor orientations.

[fmessmer]

This PR only affects cob3-9, In simulation it looks like this:

Seems like the mounting position of the arm needs to be adjusted: https://github.com/ipa320/cob_robots/blob/indigo_dev/cob_hardware_config/cob3-9/urdf/calibration_default.urdf.xacro#L58-L63

Also, the default_arm_configs need to be checked: https://github.com/ipa320/cob_robots/blob/indigo_dev/cob_default_robot_config/cob3-9/arm_joint_configurations.yaml

[ipa-nhg]

Updated and tested on cob3-9. Please merge together with this pull request the cob_robots changes: https://github.com/ipa320/cob_robots/pull/343

[floweisshardt]

LGTM