mgmt: moved signing into AppFace, code streamlining, and bug fixes

tests/management: improved callback validation

Fixed bad shared_ptr NULL checks
Fixed bad iterator decrement in InternalFace.sendInterest
Removed semi-useless constants in FibManager
Clarified ControlResponse text messages

Change-Id: Ic327a0b6b57827e401c7c3115d0ee92bae996a34
refs: #1138
diff --git a/daemon/mgmt/manager-base.cpp b/daemon/mgmt/manager-base.cpp
index 2b27f85..55787b6 100644
--- a/daemon/mgmt/manager-base.cpp
+++ b/daemon/mgmt/manager-base.cpp
@@ -40,7 +40,7 @@
   Data response(name);
   response.setContent(encodedControl);
 
-  m_keyChain.sign(response);
+  m_face->sign(response);
   m_face->put(response);
 }