major refactor in preparation for other changes
continue with refactoring

add retina support
Add the ability to set options in a config file
Remove dir parameter
Bump version to 2.0.0
Merge branch 'develop' of github.com:jwensley2/Img-Resize into develop

Conflicts:
	img_resize/library/img_resize_image.php
	img_resize/pi.img_resize.php
	readme.md
fix parameters