pr2_mechanism_diagnostics refactoring (ros ticket #4329)

[ahendrix]

'''Note:''' This will not change the ROS API or behavior of this node.

• Move code out of header file
• Change joint_stats, controller_stats maps to use boost::shared_ptrs
• Add unit test to check max/min behavior is accurate

trac data:

• Owner: watts
• Reporter: watts
• Reported at: Fri May 14 10:51:23 2010
• URL: https://code.ros.org/trac/wg-ros-pkg/ticket/4329

[ahendrix]

[watts] C-turtle

[ahendrix]

[watts] r37132 - Added unit/regression tests to input/output levels.

Still need test to check min/max output of joint values.

[ahendrix]

[watts] r37137 - Corrected internal data structures to use boost::shared_ptr. Some code out of header file

[ahendrix]

[watts] r40371