Remove Mesos integration (#2674)

Author: basil

demos/mesos/README.md

@@ -236,12 +236,6 @@
       <artifactId>mercurial</artifactId>
       <scope>test</scope>
     </dependency>
-    <dependency>
-      <groupId>org.jenkins-ci.plugins</groupId>
-      <artifactId>mesos</artifactId>
-      <version>1.0.0</version>
-      <scope>test</scope>
-    </dependency>
     <dependency>
       <groupId>org.jenkins-ci.plugins</groupId>
       <artifactId>metrics</artifactId>