Lp 1843079: Add renewals remaining to AutoRenew reactor's user data

Lp 1843079: Add renewals remaining to AutoRenew reactor's user data

Add auto_renewal_remaining and total_renewal_remaining fields to the
autorenew event's user data so that we can report the number of
renewals remaining to the patron without doing (possibly erroneous)
math in the template.  When the circulation is renewed, we use the
renewal remaining counts from the new circulation.  When the renewal
fails, we use the counts from the original circulation.

The current template is not modified to add these fields.  That is left
as an exercise for sites that want to add this information for the
convenience of their patrons.

Signed-off-by: Jason Stephenson <jason@sigio.com>
Signed-off-by: Jason Boyer <JBoyer@equinoxinitiative.org>