Remove left over system directory after test completes

Change-Id: I5f7bcfc25d7fa8912d1af19c6b5e5948afa589de
diff --git a/core/common/src/test/java/org/onosproject/common/app/ApplicationArchiveTest.java b/core/common/src/test/java/org/onosproject/common/app/ApplicationArchiveTest.java
index 1f273cc..5e77809 100644
--- a/core/common/src/test/java/org/onosproject/common/app/ApplicationArchiveTest.java
+++ b/core/common/src/test/java/org/onosproject/common/app/ApplicationArchiveTest.java
@@ -40,6 +40,7 @@
 public class ApplicationArchiveTest {
 
     static final File STORE = Files.createTempDir();
+    static final String SYSTEM = "system";
 
     private ApplicationArchive aar = new ApplicationArchive();
 
@@ -52,6 +53,7 @@
     public void tearDown() throws IOException {
         if (STORE.exists()) {
             Tools.removeDirectory(STORE);
+            Tools.removeDirectory(SYSTEM);
         }
     }
 
@@ -169,4 +171,4 @@
         aar.purgeApplication("org.foo.BAD");
     }
 
-}
\ No newline at end of file
+}