Adding Intent Impl and shell command to install simple intent
diff --git a/core/api/src/main/java/org/onlab/onos/net/intent/IntentListener.java b/core/api/src/main/java/org/onlab/onos/net/intent/IntentListener.java
new file mode 100644
index 0000000..c00c1f6
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/net/intent/IntentListener.java
@@ -0,0 +1,9 @@
+package org.onlab.onos.net.intent;
+
+import org.onlab.onos.event.EventListener;
+
+/**
+ * Listener for {@link IntentEvent intent events}.
+ */
+public interface IntentListener extends EventListener<IntentEvent> {
+}