Purgecss Versions Save

• Merge PR https://github.com/FullHuman/purgecss/pull/29 by @jsnanigans: add raw for content option to pass a raw string instead of a filepath.
• Fix incorrect logic that removes attributes selectors.
• Update dependencies.

• #14 fix merging of sets
• update dependencies
• add flow-typed lib

This release adds whitelist and whitelist patterns option.

• Config file (purgecss-config.js) #1
• Adding the CLI
• Starting the implementation of the plugins (gulp, rollup, soon webpack) #3 #4
• Better Readme, documentation