Add dependencies on dynamic reconfigure files

Occasionally the build can fail due to some targets having an
undeclared dependency on automatically generated dynamic
reconfigure files (GazeboRosCameraConfig.h for example). This
commit declares several of those dependencies.
Put some cmake lists on multiple lines to improve readability.
Simplify gazebo_plugins/CMakeLists.txt

Replace cxx_flags and ld_flags variables with simpler cmake macros
and eliminate unnecessary references to SDFormat_LIBRARIES, since
they are already part of GAZEBO_LIBRARIES.
gazebo_ros_control: use the model NodeHandle to get the robot_description parameter
Add time import

When using the -wait option the script fails because is missing the time import
replace time.sleep by rospy.Rate.sleep

time was not even imported, so I don't know
why this could ever have worked...
fix issue #38, gui segfault on model deletion by removing an obsolete call to set selected object state to "normal".
gazebo_ros_pkgs: use GetMaxStepSize() for the Gazebo simulation period
Merge pull request #143 from meyerj/patch-1

gazebo_ros_pkgs: use GetMaxStepSize() for the Gazebo simulation period
gazebo_ros_control: call writeSim() for each Gazebo world update independent of the control period
gazebo_ros_control: added GazeboRosControlPlugin::Reset() method that resets the timestamps on world reset
Merge pull request #128 from ros-simulation/cmake_fixes

Some fixes and simplifications of gazebo_plugins/CMakeLists.txt
fix spawn initial pose.  When model has a non-zero initial pose and user specified initial model spawn pose, add the two.
Merge pull request #131 from po1/fix-dep

Fix dependency issues
Merge pull request #132 from po1/fix-iterators

Fix iterator-related things
Merge pull request #134 from meyerj/gazebo-ros-control-use-model-nh

gazebo_ros_control: Use the model NodeHandle to get the robot_description parameter
Merge pull request #137 from fsuarez6/patch-1

Add time import
Merge pull request #140 from v4hn/spawn_model_sleep

replace time.sleep by rospy.Rate.sleep
Merge pull request #142 from hsu/hydro-devel

fix issue #38, gui segfault on model deletion
fix indentation