Remove Code Climate badge from README

Removed Code Climate badge from README.

Author: jnidzwetzki

README.md

@@ -10,7 +10,7 @@
 </a> <a href="https://gitter.im/bboxdb/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge">
   <img alt="Join the chat at https://gitter.im/bboxdb/Lobby" src="https://badges.gitter.im/Join%20Chat.svg">
   </a> <a href="https://repo1.maven.org/maven2/org/bboxdb/"><img alt="Maven Central Version" src="https://maven-badges.herokuapp.com/maven-central/org.bboxdb/bboxdb-server/badge.svg" />
-  </a> <a href="https://codeclimate.com/github/jnidzwetzki/bboxdb/maintainability"><img src="https://api.codeclimate.com/v1/badges/0b8b98bde4ec65bfb5b7/maintainability" /></a>
+  </a> 
 
 __Please Note:__ The master branch may be in an unstable state during development. Please use our releases for productive environments.