Remove URL module and update spec that depended on it.
Stop setting src to the rebased src in AbstractImage

The src should always represent the value given by the user.
Solve race condition in AbstractImage.

In some cases the image was not getting rebase and applied to the dom.
Refactor setting the flag
Merge pull request #1420 from francoisfrisch/rebase-url

Stop setting src to the rebased src in AbstractImage
Merge pull request #1414 from asolove/remove-url

Remove URL module and update spec that depended on it.
Add handling of cached images

A browser cached image might not trigger the onload event or we might not catch it in time.
Using Image.complete to set _isLoadingImage handle that edge case.
Clean abstract image specs
Fix specs to work in a cached environment