Makes MultiAxisDevice a CommonDevice so filters can get its input data.

Adds a CommonDevice constructor that takes just the name...good for
serialization, and that way the input DataGroup will be able to be
assigned to any DataGroup on the first call to initializeInput.
Cleans up MultiAxisDevice header file.
Adds documentation.
Moves implementations to cpp file.
Adds PoseTransform device filter.
Adds unit tests for PoseTransform device filter.
Initialize PoseTransform in unit tests.
Cleanup cmake include_directories for DeviceFilters.
Add LinearSpring viscosity term (force vector, stiffness and damping matrices)

Adjust the Massspring example to use this new parameter
Add new unit test to verify the force derivatives (stiffness and damping matrices), using a numerical derivation.
PoseTransform filters the output data sent to haptic devices.
Does not yet filter all the data.
Fix incorrect handling of boundary conditions in PlyReader
Finishes the filter functions for PoseTransform.
PoseTransform caches the NamedData indices.
PoseTransform setters are thread-safe.
Bugfix in PoseTransform, filters initial input data.
Cleans up PoseTransform unit tests.  Checks all filtered data.
Reverts MultiAxisDevice to a DeviceInterface.

Device filters do not need a CommonDevice as the input device.
Adds DataStructures::DataNames namespace in NamedData.h.

Has static const C-strings for common data names.
cpplint fixes for long lines and trailing whitespace.
In PoseTransformTest and PhantomScaffold.
Add VisualizeContactsBehavior to show vector field when there's contact
Enable VisualizeContactsBehavior in StaplingDemo
Merge branch 'master' of git.assembla.com:OpenSurgSim into feature/ViscousLinearSpring

Conflicts:
	SurgSim/Physics/UnitTests/LinearSpringTest.cpp