Pass URDF Model As Ptr To Constructor

This PR speeds up the initialization of hrl_kinematics by providing the ability to pass in a ``urdf::ModelInterface`` object that has already parsed the URDF from the param server and loaded its kinematic tree. This PR:

- Speed up initialization through optional ``urdf::ModelInterface`` parameter
- Cleans up the constructor to provide default values for all the arguments, preserving backwards compatibility. 
- Adds inline documentation of arguments
- Renames loadModel to loadKDLModel
- Stores the ``urdf::Model`` member variable in a boost ptr.
- Fixes a few style inconsistencies
- Fixes a warning from usage of deprecated functions ``tf::TransformKDLToTF``