Update JSON converter, the id is not important, applied the DRY principle.
Update the ORDER_HANDLER to use the meta_string_variable instead of meta_variable from req.
Fix, the key in meta_variable_table, use c.key instead of c.item
Update restbuck_server, remove unused class in inherit.
Update libcurl_http_client_request, to parse context headers before the
execution.
Update wgi_input_stream, commented precondition.
