0.3.0 released

This release contains the folowing changes:

• The behavior does not remove previously added rules anymore, when there is one or more overlapping field(s) among two or more field groups e0aa708
• Integration of FriendOfCake's Travis scripts
• Various CS fixes, now complying with the CakePHP coding standard
• Added Scrutinizer integration
• Added Coveralls integration
• A contribution guide
• A .editorconfig file
• Various improvements to the API docs
• Various improvements to the README/documentation
• Various minor improvements to the tests

Even though this release is a pre-release, it is production ready.

Starting with this release, the plugin is avaiable on Packagist, too.