fix bad usage of IMPORTED_IMPLIB by IMPORTED_LOCATION

ok, that was NOT FUN. To test this, just use the tf2_geometry_msgs. It DEPENDS on orocos_kdl in catkin_package() but this library does not appear in the *.cmake files. My patch fixes that.

Info at: http://www.cmake.org/Wiki/CMake/Tutorials/Exporting_and_Importing_Targets and http://www.cmake.org/cmake/help/v2.8.12/cmake.html#prop_tgt:IMPORTED_LOCATION