Sprayed files should not expire automatically if 'Expire in (days)' has been left blank

If you leave 'Expire in (days)' blank when spraying a file from Eclwatch, it is currently setting the number of expiry days 0.
This is the notation to mean, expire in the default # of days (as per Sasha 'expiryDays' setting).

It should not set any expiry by default when spraying a file, only if you've explicitly asked for it.

As well as avoiding setting it erroneously as now, we may also want a UI tick box feature to say something like "Expire in default number of days (7 days)", where "7" is fetched from the current default setting.