Add shields.io badges
New version of Composer can resolve version automagically

http://blog.doh.ms/2014/10/13/installing-composer-packages/
Copy paste is baad mmmkay
Install development version for now
Add missing comma to composer.json
Merge branch 'development'
Add coverage badge
Move common methods to MutatorAbstract
Assume most will use intervention/image

Less boilerplate code needed.
Upgrade to intervention/image 2.x
Parsing is done by mutators so test them in mutator tests
Add scale and crop mutator
Update headers and meta
Calling $mutator->parse() also automagically sets the options
Improve coverage
Not sure why --prefer-source was there