Install files to the correct directories

[gleichdick]

I was building the iiwa stack from source to an install space (set up via catkin config --install ...), so everything is supposed to be under <workspace>/install/{lib, share, bin}. At building, cmake complained that the iiwa_ros library could not be found:

..........................................................................................................................................................
Finished  <<< iiwa_ros                                       [ 18.6 seconds ]                                                                             
Starting  >>> iiwa_hw                                                                                                                                     
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Errors     << iiwa_hw:cmake /home/user/ros2/iiwa/logs/iiwa_hw/build.cmake.005.log                                                                       
CMake Error at /home/user/ros2/iiwa/install/share/iiwa_ros/cmake/iiwa_rosConfig.cmake:173 (message):
  Project 'iiwa_hw' tried to find library 'iiwa_ros'.  The library is neither
  a target nor built/installed properly.  Did you compile project 'iiwa_ros'?
  Did you find_package() it before the subdirectory containing its code is
  included?
Call Stack (most recent call first):
  /home/user/ros2/melodic/share/catkin/cmake/catkinConfig.cmake:76 (find_package)
  CMakeLists.txt:7 (find_package)

I noticed that the install() commands were missing in the CMakeLists.txt files, so I adapted them from other ROS projects