Add libspdlog-dev to the Ubuntu Dockerfile. (#662)
Add libspdlog-dev to the Ubuntu Dockerfile. (#662)

We should install this from the system so that we don't build
the vendor package.  While we are in here, remove the now
unused liblog4cxx package.

Signed-off-by: Chris Lalancette <281cd07d7578d97c83271fbbf2faddb83ab3791c@openrobotics.org>
ros2/ci,ros2/ci,ros2/ci