Shorten introductory text for posting new sightings. (#535)
Improve order of sighting form fields.

In preparation for adding a date field, order the fields more
like the information display on the sighting page. (#535)
Add Date field to sighting form. (#535)
Allow period at the end of address segment of location.

Example: Boylston St., Boston, MA
(#535)
Save the date field value on sighting form submit. (#535)
Enable styling of date picker on sighting form. (#535)
Edit line on sighting page showing contributor and date.

Remove unneeded timestamp and rearrange to match format used
in marker popups on Sightings Locator maps. (#535)
Update column name on the Manage Sightings page. (#535)
Fix date field validation bug when editing sightings. (#535)
Widen the Manage Sightings location column. (#535)
Correct some details with sighting dates.

Clean up old code to set the initial date. Change the form
field to use a datetime object instead of a date object,
even though a date is all the user can input. Set the
time behind the scenes to keep inputs ordered in the
sequence of entry on the selected date. (#535)