Add DisableNode keyword

This new special keyword allows one configuration
to disable another entity. This is useful for cases
where a system without a chassis desires one configuration,
but when it is in a chassis, it requres a different
configuration.

Tested: Verified DisableNode disabled configurations, and
that Bind still worked

Change-Id: I3ff1f8bca7c7dffd5210ddea238877c65c859068
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index c6f7d8a..960f76d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -58,7 +58,7 @@
 
     externalproject_add (
         nlohmann-json GIT_REPOSITORY "https://github.com/nlohmann/json.git"
-        GIT_TAG d2dd27dc3b8472dbaa7d66f83619b3ebcd9185fe SOURCE_DIR
+        GIT_TAG 456478b3c50d60100dbb1fb9bc931f370a2c1c28 SOURCE_DIR
         "${CMAKE_BINARY_DIR}/nlohmann-json-src" BINARY_DIR
         "${CMAKE_BINARY_DIR}/nlohmann-json-build" CONFIGURE_COMMAND ""
         BUILD_COMMAND "" INSTALL_COMMAND mkdir -p