Merge pull request #1 from mylene-campana/master

New script corresponding to gravity.launch
Cosmetic changes
Move hrp2.py to hpp-hrp2 package.
Update to new interface of hpp-model-urdf.
Update to new error handling policy in hpp-corbaserver

  - corba requests do not return a status anymore. If an error occurs, an
    exception is thrown.
Update to modification in hpp-model-urdf interface.

  - create empty robot and pass it to loadxxxModel.
Merge branch 'master' of https://github.com/humanoid-path-planner/test-hpp