Bug when processing multiple images on the same page

When processing mulitple images all background styling is being applied to the same parentNode, i.e. the parentNode of the last processed image. This is due to the asynchronous nature of the RGBaster processing.

Demos of the original and working (pull request) version.

http://grephix.nl/dump/github/adaptive-backgrounds-gh-pages/original/
http://grephix.nl/dump/github/adaptive-backgrounds-gh-pages/working/