use current position when starting (forward_command) position_controllers

effort and velocity (forward_command) controllers still use 0.0

The template class now only contains the declaration for ```starting()```. The implementation moved to the respective controllers.

This is related to #104
I guess you are right.
In case the ´´´joint_´´´ cannot return ´´´getPosition()´´´ it should have failed earlier already!
I removed the ```try-catch``` part