[mintupdate] feature request: override default refresh time on PPAs

[deutrino]

I'm running mintupdate 4.8.1 on Mint 17.1 "Rebecca," cinnamon edition.

I've added a couple PPAs from which I get software updates. One of these is an ill-behaved PPA which seems to push nightlies, so I get an update notification for a (very large) application on a near-daily basis. I could work around the problem by reducing the global refresh interval from the default of 30 minutes to something like 3-7 days (!), but that's not a good idea for fairly obvious security reasons.

I'd like to have a property on PPA entries such that I can override their refresh interval. Then I could tell mintupdate to only poll this particular PPA once a week.