Support entering exact date/time values into the After and Before textboxes

If the After or Before textbox contains a hyphen, interpret the textbox as a date value and filter the results based on the date/time(s) specified. If only a date is entered, the time is assumed to be 12:00am on that date.
Merge pull request #6 from CyanBeard/master

Support entering exact date/time values into the After / Before textboxes