Add back deprecated functions to support gazebo 3.1

Gazebo 3.0 will be released with DART 3.0 at Apr 11. DART 4.0 will be supported by Gazebo 3.1 not breaking ABI of Gazebo in next one or two months. Not to break ABI, DART 4.0 needs to keep deprecated API which is exposed at header files of Gazebo 3.0.

We found the API we need to bring back are `EllipsoidShape::setDim()` and `BoxShape::setDim`.