made PNG and JPG extensions case insensitive
Merge pull request #53 from phpmycoder/fix/case-insensitive-extensions

Made PNG and JPG extensions case insensitive
Cache images

Closes #40
Various tweaks for #40
Use unicode arrows
Set the `progressive` to true by default and level to 7

This is now feasible since we cache the images, so it will only be run once.
Update deps
Update readme about caching of images
Switch to Chalk for colors

https://github.com/sindresorhus/chalk
Rename test file
Use `files` property in package.json
Limit async operations to the number of CPUs
Improve docs

Closes #48
Add support for gifsicle

Closes #54
Add support for pngquant

Fixes sindresorhus/node-pngquant-bin#1.
Merge pull request #55 from kevva/pngquant

Add support for pngquant
0.2.0
Update changelog and readme
missing comma in Example config
Merge pull request #59 from leonardosouza/master

missing comma in Example config