Fix broken tests on non-english setup (#569)

Author: dreis2211

pom.xml

@@ -282,6 +282,9 @@
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-surefire-plugin</artifactId>
                 <version>2.22.2</version>
+                <configuration>
+                    <argLine>-Duser.language=en -Duser.region=GB</argLine>
+                </configuration>
             </plugin>
             <!-- JACOCO added for code coverage -->
             <plugin>