add serenity bdd

worked with this framework for half a year now, it's great. community and development is active.
unique selling points: implements the screenplay pattern, two-way jira integration ...

README.md

@@ -923,6 +923,7 @@ A curated list of awesome Java frameworks, libraries and software.
 - [JBehave](http://jbehave.org) - Extensively configurable framework that describes stories.
 - [JGiven](http://jgiven.org) - Provides a fluent API which allows for simpler composition.
 - [Lamdba Behave](https://github.com/RichardWarburton/lambda-behave) - Aims to provide a fluent API to write tests in long and descriptive sentences that read like plain English.
+- [Serenity BDD](http://serenity-bdd.info/) - Automated Acceptance testing and reporting library that works with Cucumber, JBehave and JUnit to make it easier to write high quality executable specifications.
 
 #### Fixtures