http: enable clirr:check on mvn install & failOnError true

https://codereview.appspot.com/13761045/

Author: Yaniv Inbar

pom.xml

@@ -361,7 +361,7 @@
         <plugin>
           <groupId>org.codehaus.mojo</groupId>
           <artifactId>clirr-maven-plugin</artifactId>
-          <version>2.5</version>
+          <version>2.6</version>
         </plugin>
         <plugin>
           <groupId>org.codehaus.mojo</groupId>
@@ -551,9 +551,15 @@
         <configuration>
           <comparisonVersion>1.17.0-rc</comparisonVersion>
           <ignoredDifferencesFile>${basedir}/../clirr-ignored-differences.xml</ignoredDifferencesFile>
-          <failOnError>false</failOnError>
           <logResults>true</logResults>
         </configuration>
+        <executions>
+          <execution>
+            <goals>
+              <goal>check</goal>
+            </goals>
+          </execution>
+        </executions>
       </plugin>
       <plugin>
         <groupId>org.codehaus.mojo</groupId>