Add threshold for Cartesian Path motion execution

[rkojcev]

Just a simple add on which will decide whether or not a Cartesian path is to be executed by the robot.
If the success of the Cartesian Path is above certain threshold then the MoveIt will execute this path if not the robot will not move at all.
For example if we have 8% success of Cartesian path of execution, this path should not be executed by the MoveIt.
I know this number is very user depended and different users would like to have different numbers but it would be nice feature to add...