Debug dates / timezone issue; Heroku Keepalive
	- I believe I've finally fixed the bug with dates, datetimes, and time zones.
		I think the core issue was that I was passing date objects to an SQL
		query against datetime fields; the date objects were being provided literally,
		rather than being converted to datetimes having the proper time zone.
		Remember that datetimes are stored in UTC format in the database,
		but Date.today is contingent on the present time zone.
		As a rule, never provide a Date object to a query; convert it to Datetime
		first.
	- I'm trying to set up a Rake task to keep the Heroku instance alive.
		(Single-dyno Heroku apps are suspended after 1 hour of inactivity, sensibly.)
		Testing an initial version of that rake task.
fix Heroku keepalive task