Fix build failures

The first fix is for a regression caused by a889ef8b768861231a67b78781514d834f631b8e. Gazebo is clearly still needed at https://github.com/ros-simulation/gazebo_ros_pkgs/blob/indigo-devel/gazebo_ros_control/CMakeLists.txt#L17 and was available at build time because of `gazebo_ros`.

The second fix adds `angles` as a dependency. I've seen this in other packages in Indigo, so I'm pretty sure an upstream package changed. In any case, it is referenced at https://github.com/ros-simulation/gazebo_ros_pkgs/blob/indigo-devel/gazebo_ros_control/src/default_robot_hw_sim.cpp#L60 and should therefore be a dependency.

This is causing failures on the buildfarm: http://jenkins.ros.org/job/ros-indigo-gazebo-ros-control_binarydeb_saucy_amd64/14/console

Thanks!

--scott