Minor issue with logo location dict in create_plots.py

[EdwardSafford-NOAA]

Suggest some small changes to the logo loc_dict in plot_logo() in create_plots.py. This is a low priority issue.

In my tests right and center right produced the same results, so I'd argue for dropping right (there is no left but there is a center left). Also I suggest renaming bottom left and bottom right to lower left and lower right to make them consistent with the other uses of upper/lower.