Don't load pixel until load() is called on ad

[ericholscher]

Feedback from a user:

I see that a tracking pixel is loaded on the page (px.gif - twice) if theethicalads.min.js script is loaded onto the page, regardless of if there is a call to ethicalads.load() or not. I'm wondering if that might be messing with some of the metrics? As we discussed before, I don't load ads for anyone who has paid for a service / product from us, but I do have the ethicalads.min.js included on all pages, and then a bit of JS generated by PHP decides if ethicalads.load() should be run or not.

We can likely hook that logic into the ad display code, instead of being loaded when the JS is loaded, to avoid this. No reason to run extra logic if we can avoid it.

It looks like the logic should already be doing this, so guessing there's something else happening here:

ethical-ad-client/index.js

Lines 617 to 618 in 52906d5

	if (index === 0 && placement && !force_load) {
	placement.detectABP(ABP_DETECTION_PX, function (usesABP) {

[davidfischer]

This is definitely not messing with our metrics or with what we report to the AcceptableAds folks. However, I'll review it to make sure it isn't doing anything unnecessary.