Add hour and week as options to the heatmap charting function showing number of work orders completed in a given time frame.

[brl1906]

1. refactor the heatmap weekday_complete and month_complete to include hour and week.

2. bring this together in one function using separate functions to check the value of z_value argument in the function and call that function within the larger function to handle the separate cases. (See Clean Code, Robert Martin chapter on making good functions for guidance here.)