Small INT app and UI improvements

[INT App]
 - Load INT report config when activate the app
 - Remove config listener and config factory from app when deactivate
 - Check INT intent map before remove a INT intent
 - Add more check to check the input from frontend UI
 - Change log level of UI message handler from info to debug

[GUI1]
 - Reformat CSS code
 - Remove '$scope.sendIntConfigString' which breaks the UI
 - Fix regular expression that matches IP prefix
 - Remove "required" attribute from all field
 - Add additional check to prevent sending invalid input to backend
 - Use 'let' instead of 'var' to limit the scope of variable
 - Make INT button aligned with other elements
 - Show message if any field is invalid

[GUI2]
 - Remove INT collector config panel
 - Reformat HTML code
 - Fix regular expression which matches the IP prefix

[API]
 - Add default value '0' for all fields in INT device config
 - Skip checking the metadata types when building the IntObjective since
   some pipeline won't need it

Change-Id: Ica260c35d411336419f77eb0de5787e943dc1887
diff --git a/core/api/src/main/java/org/onosproject/net/behaviour/inbandtelemetry/IntDeviceConfig.java b/core/api/src/main/java/org/onosproject/net/behaviour/inbandtelemetry/IntDeviceConfig.java
index e1790bc..a21a2ae 100644
--- a/core/api/src/main/java/org/onosproject/net/behaviour/inbandtelemetry/IntDeviceConfig.java
+++ b/core/api/src/main/java/org/onosproject/net/behaviour/inbandtelemetry/IntDeviceConfig.java
@@ -170,12 +170,11 @@
      * An IntConfig object builder.
      */
     public static final class Builder {
-
-        private IpAddress collectorIp;
-        private TpPort collectorPort;
-        private MacAddress collectorNextHopMac;
-        private IpAddress sinkIp;
-        private MacAddress sinkMac;
+        private IpAddress collectorIp = IpAddress.valueOf(0);
+        private TpPort collectorPort = TpPort.tpPort(0);
+        private MacAddress collectorNextHopMac = MacAddress.valueOf(0);
+        private IpAddress sinkIp = IpAddress.valueOf(0);
+        private MacAddress sinkMac = MacAddress.valueOf(0);
         private TelemetrySpec spec = TelemetrySpec.INT;
         private boolean enabled = false;
         int minFlowHopLatencyChangeNs = 0;