[wip/genom3-ros] Update to 1.7

Changes since 1.6:
 . Fix the generation of serialization methods in presence of 'native' types
 . Fix a typo in the client/c pkgconfig file (wrong middleware name)
 . Install client/c headers and libraries in a middleware-specific location
 . Fix serialization for arrays of structured types
 . Fix ROS_PACKAGE_PATH setting
 . Properly quote exception detail when reporting a JSON unknown exception
 . Fix deserialization of void exceptions in the C client