[2.2.0rc1] Release preparation
[2.2.0rc1] Release preparation

- Updated all component composer.json files to reflect new branch aliases
- Updated changelog
- Updated readme

matbech/zend-mail,rapidsoft-de/zend-mail,MadCat34/zend-mail,mleko/zend-mail,Xerkus/zend-mail,stefanotorresi/zend-mail,basz/zend-mail