mgmt: InternalFace processes Interest asynchronously

This avoids forwarding's incoming Data pipeline to be called
within incoming Interest pipeline - this property holds for
other faces, and is expected by forwarding.

refs #1419

Change-Id: I3eb1ca84830d5d8aefe0ae67a562acdd835ca5ca
diff --git a/tests/mgmt/face-manager.cpp b/tests/mgmt/face-manager.cpp
index 9cfca66..d439ea4 100644
--- a/tests/mgmt/face-manager.cpp
+++ b/tests/mgmt/face-manager.cpp
@@ -653,6 +653,7 @@
          command->getName(), 400, "Malformed command");
 
   getFace()->sendInterest(*command);
+  g_io.run_one();
 
   BOOST_REQUIRE(didCallbackFire());
 }