Additional log feedback when load_controller fails

When loading a controller fails bacause its configuration was not found on the
parameter server, show the namespace where the parameters are expected to help
debugging.
Use demangled type names when available. Fixes #36.

Type names are used in different interfaces  such as hardware_interface and
controller_interface. When symbol demangling is available (currently gcc 3.0+),
operate on demangled names, as they are more convenient for human reading, eg.

hardware_interface::VelocityJointInterface

instead of

N18hardware_interface22VelocityJointInterfaceE
Merge branch 'master' of github.com:willowgarage/ros_control
Merge pull request #37 from pal-robotics/master

Issue #36 fix.