Please rename include/json directory to include/jsoncpp since this reflects the project name as "#include <jsoncpp value.h="">" and permits name conflicts with other json libraries.
Some formatting went wrong. The include would look like #include "jsoncpp/value.h"
jsoncpp is slightly more unique than json, but the problem would still exist.
When you use a 3p lib, you might have to search-and-replace the include lines. We could make that a build option, but it's not that hard for you to do with post-processing.
A fair criticism would be that the Json:: namespace is used too often. Maybe we can change that someday.