More receipt macros

Patron/Staff Middle Name and patron expiration date.

Including a YMD format variant of the latter.

Signed-off-by: Thomas Berezansky <tsbere@mvlc.org>
Signed-off-by: Pasi Kallinen <pasi.kallinen@pttk.fi>
Signed-off-by: Jason Stephenson <jstephenson@mvlc.org>