libnetconf UPDATE YANG data configuration

Configuration based on YANG data. Open 2 ssh channels on one
session. Pubkey,interactive,pw,none SSH authentication working. SSH
message callback not a callback anymore, handle SSH messages manually.
ietf-netconf-server and all models it imports added and a libnetconf2 own model
with augments. And finally only local-definition of keys supported. 2 tests.
NBC API changes.
diff --git a/tests/config.h.in b/tests/config.h.in
index 42a8078..cf58c40 100644
--- a/tests/config.h.in
+++ b/tests/config.h.in
@@ -19,6 +19,7 @@
 #endif
 
 #define TESTS_DIR "@CMAKE_SOURCE_DIR@/tests"
+#define MODULES_DIR "@CMAKE_SOURCE_DIR@/modules"
 #define BUILD_DIR "@CMAKE_BINARY_DIR@"
 
 @SSH_MACRO@