Merge pull request #435 from y-higuchi/permgen_tuning

Assure larger PermGen size to avoid PermGen errors on some environment.
diff --git a/pom.xml b/pom.xml
index 935b0eb..ae020cf 100644
--- a/pom.xml
+++ b/pom.xml
@@ -81,6 +81,7 @@
             <exclude>**/*TestCase.java</exclude>
           -->
           </excludes>
+          <argLine>-XX:MaxPermSize=256m</argLine>
         </configuration>
       </plugin>
       <!-- exec:java -->