Don't display "no ads" javascript

If an ad group is enabled, but there are no ads in it, the JavaScript spits "No active ads were found in the group "highlights4"". This is relatively useless - whereas your intent (to indicate to the admin that there's no ads in the group) is to inform, you've done so in the wrong place. At NHPR, we have, for example, four ad groups called "highlight1", 2, 3, and 4. All four are enabled all the time. Occasionally all four are full because we have four awesome features. Sometimes, however, we only have three or two. Or even just one. With the JS output, we now can't run an ad for a week-long highlight and then have it disappear: we have to very carefully make sure that someone manually disables the Ad group block, otherwise we risk the unsightly error message to our users. This is a pain.

Suggestion: move the warning into a watchdog block (or perhaps, an HTML comment if you're trying to save the bootstrap) and don't show anything if there are no ads enabled. I know, I know: I suspect the warning was prevalent and obvious because of the incredible "ads don't show" support queue. Fine. If you don't want to remove it entirely, at least give me an admin option to disable it (but again, sadly, at the cost of a variable_get bootstrap).