synchronize with drcsim plugins
per pull request comments
Merge branch 'hydro-devel' into synchronize_with_drcsim_plugins
change includes to use brackets in headers for export
Merge branch 'hydro-devel' of github.com:ros-simulation/gazebo_ros_pkgs into synchronize_with_drcsim_plugins
update gazebo includes
Merge remote-tracking branch 'origin/synchronize_with_drcsim_plugins' into groovy-devel
Make gazebo includes use full path

In the next release of gazebo, it will be required to use the
full path for include files. For example,
include <physics/physics.hh> will not be valid
include <gazebo/physics/physics.hh> must be done instead.
Merge branch 'fix_gazebo_includes' of github.com:ros-simulation/gazebo_ros_pkgs into groovy-devel