Add pipeline status to readme.

README.md

 # P³LS³
 **P**redictable **P**arallel **P**atterns **L**ibrary for **S**calable **S**mart **S**ystems
 
+Master Branch: [![pipeline status](http://lab.las3.de/gitlab/las3/development/scheduling/predictable_parallel_patterns/badges/master/pipeline.svg)](http://lab.las3.de/gitlab/las3/development/scheduling/predictable_parallel_patterns/commits/master)
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 ## Project Structure
 
 The project uses [CMAKE](https://cmake.org/) as it's build system,