[#39] Use ImageMagick to get sampling factor and orientation
[#29] Handle fatal errors

- Add php shutdown handler which adds a 500 response header, so the response triggers the .error() callbacks.
- Show error and disable busy state
Check if file exists only if input changed
Add ext-imagick to composer.json
Querystring: prefer 'title' over 'imageUrl'

Both parameters are handled the same way anyway, and 'title' is shorter
Merge branch 'master' into deploy

Conflicts:
	composer.json
	public_html/common.php
	public_html/crop.js
	src/Image.php
mcrypt also needed
Vagrant setup - a start