**breaking change**: Switch Face and related classes to v2::KeyChain

security::v2::KeyChain is now exposed as ndn::KeyChain, which should
ensure that dependent code can be mostly compiled.  However, expect code
that explicitly uses the old KeyChain interface to be broken.

Change-Id: I7330d0250d92f3f0f2570ab6d0214ab3dfdd18cc
Refs: #3098
diff --git a/src/security/command-interest-signer.cpp b/src/security/command-interest-signer.cpp
index 0d2f82f..3704a7e 100644
--- a/src/security/command-interest-signer.cpp
+++ b/src/security/command-interest-signer.cpp
@@ -47,7 +47,7 @@
   return name;
 }
 
-CommandInterestSigner::CommandInterestSigner(v2::KeyChain& keyChain)
+CommandInterestSigner::CommandInterestSigner(KeyChain& keyChain)
   : m_keyChain(keyChain)
 {
 }