Merge pull request #6 from arthurdarcet/master

Compute the hash of a requested image with the md5 of the filename instead of the file content itself
Update dependencies
Add ability to set globaly or per-instance the final quality
Update README.md
Update README.md
Rewrite classes to new ServiceProvider model
Use Imagine's thumb method now that the behavior is fixed
Make height fallback to width if not provided in thumb
Add some tests
Switch to tabs
Bump version
Fix PHP 5.3 compatibility
Monkey patch: serve assets over a custom CDN