#1 updated signup info in action log

[Jeremy Shaver]

WHen updating a signup, the OLD signup information
could be added to the action log (in addition to the
NEW signup info). This would make it easier to figure
out exactly what someone was TRYING to do when they
updated a signup. Currently it only shows the NEW
signup info and you can't tell what the original
time/date/resource was before the user changed it (you
have to dig through the log and see if you can find the
matching signup #)