Disabled check "DoubleCheckedLocking"

Eclipse plugin produces errors and we do not use self created locking.
This should be removed if eclipse plugin can handle this.

ARSnova-checkstyle-checker.xml

@@ -158,7 +158,7 @@
         <!-- Checks for common coding problems               -->
         <!-- See http://checkstyle.sf.net/config_coding.html -->
         <module name="AvoidInlineConditionals"/>
-        <module name="DoubleCheckedLocking"/>    <!-- MY FAVOURITE -->
+        <!-- module name="DoubleCheckedLocking"/-->    <!-- MY FAVOURITE -->
         <module name="EmptyStatement"/>
         <module name="EqualsHashCode"/>
         <module name="HiddenField"/>