Bumping up surefire plugin version

+ This should address the CI build JVM hang bug if we have a
  bad/failing testcase (like the recent jetty-proxy issues)
+ See bug https://issues.apache.org/jira/browse/SUREFIRE-524

pom.xml

@@ -294,7 +294,7 @@
         <plugin>
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-surefire-plugin</artifactId>
-          <version>2.18.1</version>
+          <version>2.19</version>
           <configuration>
             <argLine>-showversion -Xmx1g -Xms1g -XX:+PrintGCDetails</argLine>
             <failIfNoTests>false</failIfNoTests>