Merge branch 'master' into v1.5.4rc6

Author: devGregA

README.md

@@ -69,7 +69,7 @@ should give you an idea of how to use DefectDojo for your own team.
 ![Slack](https://raw.githubusercontent.com/DefectDojo/Documentation/master/doc/img/slack_rgb.png)
 
 Realtime discussion is done in the OWASP Slack Channel, #defectdojo.
-[Get Access.](https://join.slack.com/t/owasp/shared_invite/enQtNjExMTc3MTg0MzU4LWQ2Nzg3NGJiZGQ2MjRmNzkzN2Q4YzU1MWYyZTdjYjA2ZTA5M2RkNzE2ZjdkNzI5ZThhOWY5MjljYWZmYmY4ZjM)
+[Get Access.](https://owasp-slack.herokuapp.com/)
 
 ![Twitter](https://raw.githubusercontent.com/DefectDojo/Documentation/master/doc/img/Twitter_Logo.png)