tests: test IP transports under various combos of address family/scope

In particular, link-local addresses are now tested as well.

Additionally, WebSocketTransport send/receive tests are extended
to check transport counters.

Change-Id: I5b35f498a5d8d70cb1f7a2bea3ce99d22370e050
Refs: #1428
diff --git a/tests/daemon/face/unix-stream-transport-fixture.hpp b/tests/daemon/face/unix-stream-transport-fixture.hpp
index 0101f10..634bb9a 100644
--- a/tests/daemon/face/unix-stream-transport-fixture.hpp
+++ b/tests/daemon/face/unix-stream-transport-fixture.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2014-2015,  Regents of the University of California,
+/*
+ * Copyright (c) 2014-2017,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -87,6 +87,12 @@
   {
   }
 
+  std::pair<bool, std::string>
+  checkPreconditions() const
+  {
+    return {true, ""};
+  }
+
   void
   initialize()
   {