Initial commit of hebiros_wrapper convenience class

[josephcoombe]

Small convenience class we've been using to reduce boilerplate code when using the hebiros package.

[iamtesch]

This is awesome -- I'm still trying to figure out the right way to merge this in, but I like having more boilerplate handled by the API!

[josephcoombe]

Here's a potential template/model for convenience/wrapper classes:
The orocos_kinematics_dynamics library (KDL): https://github.com/orocos/orocos_kinematics_dynamics
A Georgia Tech Python Wrapper for common patterns with KDL: https://github.com/gt-ros-pkg/hrl-kdl/blob/indigo-devel/pykdl_utils/src/pykdl_utils/kdl_kinematics.py

[josephcoombe]

Note, should be updated to use local ROS namespaces instead of absolute if #106 is merged