Add TimePlotDate format for input to matplotlib plot_date()
Add test of TimePlotDate
Add example of using plot_date format with plt.plot_date()
Add time format for datetime.datetime objects
Update error messages for Time input validation
Generalize way of identifying formats where format kwarg is optional
Add tests for datetime format
Update docs for datetime format
Update CHANGES
Minor tweaks in time docs
Merge pull request #860 from taldcroft/time-plot-date

Add plot_date and datetime Time formats