Issue/heavy payload

When lifting heavy payloads with the ur5/ur10 the controller tends to trigger a "forced stop". To avoid  this it is necessary to set the correct payload so that the controller can predict the appearing forces due to the payload.

In this PR a new class called URServiceProvider is implemented as  interface for sending parameters to the robot during runtime.

The payload can be set between [0.0; 20.0] . It is necessary to set the correct payload when working with the force/torque from https://github.com/ros-industrial/universal_robot/pull/77