Fixed issue where the distance to in view was always saying that it was in the view

So before, Math.max was getting an extra 0 as a parameter which would always win and then minus the variance from that would always result in the distanceFromTrigger to always be less than 0.  So I removed the 0. 

There was also another bug where if an img is not in the view yet, the Math.max call would return a negative number.  Then you subtract the variance from there and it's always a negative number.  So this is backwards from the desired functionality which is why I added the -1 * there.
It does.  If you open up the demo and then inspect all of the images on the page, the images at the bottom have already had their data-postpone-src value placed into the src attribute even if it has not met the postpone threshold yet.  In the below image, only the first img tag should be loaded, but all of them are.

![image](https://cloud.githubusercontent.com/assets/4642727/4869117/513e10e4-6148-11e4-94e4-4656a8c9fa2c.png)