Remove duplicate dependency (prometheus#232)

Author: bluehallu

simpleclient_servlet/pom.xml

@@ -73,11 +73,5 @@
             <version>1.9.5</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.mockito</groupId>
-            <artifactId>mockito-core</artifactId>
-            <version>1.9.5</version>
-            <scope>test</scope>
-        </dependency>
     </dependencies>
 </project>