Removed the setServiceDirectory() method from the base web resource

This is a testing only API and potentially dangerous to allow to be public.
I modified the tests that use it to set the value using TestUtils.setField()

Change-Id: Ic590f4641f4e3de208dffa16b3df9a9a2106114b
diff --git a/web/api/src/test/java/org/onosproject/rest/resources/StatisticsResourceTest.java b/web/api/src/test/java/org/onosproject/rest/resources/StatisticsResourceTest.java
index 66b6eb0..a1bbccb 100644
--- a/web/api/src/test/java/org/onosproject/rest/resources/StatisticsResourceTest.java
+++ b/web/api/src/test/java/org/onosproject/rest/resources/StatisticsResourceTest.java
@@ -24,7 +24,6 @@
 import org.junit.Test;
 import org.onlab.osgi.ServiceDirectory;
 import org.onlab.osgi.TestServiceDirectory;
-import org.onlab.rest.BaseResource;
 import org.onosproject.codec.CodecService;
 import org.onosproject.codec.impl.CodecManager;
 import org.onosproject.net.Link;
@@ -92,7 +91,7 @@
                         .add(StatisticService.class, mockStatisticService)
                         .add(CodecService.class, codecService);
 
-        BaseResource.setServiceDirectory(testDirectory);
+        setServiceDirectory(testDirectory);
     }
 
     /**