Move to Clippings organisation

[hkdobrev]

We'd like to move all actively maintained packages to @clippings organisation on GitHub and the clippings vendor name on Packagist.

Steps:

• Update license and readme
• Transfer repository to https://github.com/clippings.
• Change name in composer.json to clippings/swiftmailer-css-inliner.
• Publish clippings/swiftmailer-css-inliner to Packagist.
• Mark the openbuildings/swiftmailer-css-inliner package as deprecated.
• Point the deprecated openbuildings/swiftmailer-css-inliner to clippings/swiftmailer-css-inliner on Packagist.
• Release new minor version on clippings/swiftmailer-css-inliner.
• Release new minor version on openbuildings/swiftmailer-css-inliner.
• Stop releasing new versions on openbuildings/swiftmailer-css-inliner.
• Change Openbuildings namespace to Clippings in a new 0.x release?