messed up time variable with floater_convert

[rabernat]

I did the following on habanero

floater_convert --input_dir /rigel/ocp/users/as4479/MITgcm/llc_agulhas/3dfloats_hourly --progress --output_format netcdf --output_dir /rigel/ocp/users/ra2697/float_visualization --step_time 25 --ref_time 2011-01-01 float_trajectories

This converts @anirban89's output data into netcdf. It works fine if I don't specify step_time or ref_date. But if I do, the time variable is just zero for all the netcdf files.

What could be going on here.

cc @geosciz