Router: Add "router delete" command using SDK

This patch adds "router delete" command to osc using sdk.

Change-Id: I47d0ca7f7984942ffceaeb1c9ac69efd09145f40
Implements: blueprint neutron-client
Partial-bug: #1519503

doc/source/command-objects/router.rst

@@ -44,6 +44,22 @@ Create new router
 
     New router name
 
+router delete
+--------------
+
+Delete router(s)
+
+.. program:: router delete
+.. code:: bash
+
+    os router delete
+        <router> [<router> ...]
+
+.. _router_delete-router:
+.. describe:: <router>
+
+    Router(s) to delete (name or ID)
+
 router list
 -----------