Shorten device manager impl test

src/test/java/net/floodlightcontroller/devicemanager/internal/DeviceManagerImplTest.java

@@ -335,7 +335,7 @@ public class DeviceManagerImplTest extends FloodlightTestCase {
         // Get the listener and trigger the packet in
         mockFloodlightProvider.dispatchMessage(mockSwitch, this.packetIn);
         
-        Thread.sleep(3000);
+        Thread.sleep(100);
         
         // Get the listener and trigger the packet in
         mockFloodlightProvider.dispatchMessage(mockSwitch, this.packetIn);