In asebahttp, missing OPTIONS for PUT request

Created by: ypiguet-epfl

In asebahttp, cross-origin requests to write new Aesl program with PUT doesn't work because the browser first preflights the request with OPTIONS (see HTTP access control (CORS) at MDN). OPTIONS isn't implemented in asebahttp. Chrome throws the error OPTIONS http://127.0.0.1:3000/nodes/thymio-II net::ERR_EMPTY_RESPONSE. Suggestion: implement OPTIONS in file switches/http/http.cpp, methods HttpRequest::initialize and HttpInterface::routeRequest (see OPTIONS at MDN).