extrinsic_cal: missing find_package() for yaml-cpp

[gavanderhoorn]

The yaml-cpp library is added as a linking dependency in:

target_link_libraries(industrial_extrinsic_cal_ceres
  yaml-cpp ${catkin_LIBRARIES})

without first a find_package().

ROS depends on it as well, so it will probably always be present when industrial_calibration is build, but it might be a good idea to find_package() it.

[gavanderhoorn]

This is still an issue in #29. A solution for #30 might depend on proper use of find_package(..) for yaml-cpp.

[VictorLamoine]

@drchrislewis This (and #50) can be closed as #62 fixed this issue, here and here.