#85 Specify expire-length with drop-down menu

[Matthew Leingang]

If I had a dime for every time I pulled out my calculator to find
60*60*24...

Why not have a text field to specify the length of time, then a
drop-down to pick the "units" E.g., "seconds", "minutes", "hours",
"days", "weeks"?

"Never" and "Always" should also be options.

And while we're at it, "Expire length:" seems overly opaque. Why
not something more illustrative like "Reload every:"