Laravel 3

Hi Robert,
As mentioned via email I send you my pull request for the laravel-3 branch.
I added three things:
- a small change to add more info to an Exception message
- a setting for JPEG quality. This had been killing me as the dimension-wise much small cropped file often were double or even triple the file size of the original. Setting JPEG quality to 90 percent did the deal :)
- last but nto least the change I wrote you about, the possibility to keep the max_crops stable by deleting the oldest crop if a new one is requested.

Hope you like it, Code quality and commenting can take a tweak though I guess ;)

Cheers,
Michael