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.
For now the implementation is using Eiffel cURL library.
It requires Eiffel cURL coming with next EiffelStudio 7.0 (or from eiffelstudio's repo from rev#87244 )