Upgrade to Surefire 2.18.1

Changelog:

http://maven.40175.n5.nabble.com/Apache-Maven-Surefire-Plugin-2-18-1-Released-td5821513.html

pom.xml

@@ -113,7 +113,7 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>2.18</version>
+        <version>2.18.1</version>
         <configuration>
           <parallel>classes</parallel>
           <threadCount>1</threadCount>