add domain= queryarg to the .well-known fetch

This should allow multiple primaries to delegate control to the same
server, by letting the server know which domain we're interested in.
This is similar to how the HTTP "Host" header enables named-based
virtual hosting. Both the Verifier and the user agent (specifically the
/wsapi/address_info handler) will add this argument. Servers which host
only one key can ignore it.

Also allow arbitrary queryargs in bin/proxy, otherwise it denies
requests with queryargs.

This should help Bigtent do dynamic .well-known lookups.

bin/proxy

@@ -19,7 +19,7 @@ var addy = config.has('bind_to.host') ? config.get('bind_to.host') : "127.0.0.1"
 // set a maximum allowed time on responses to declaration of support requests
 forward.setTimeout(config.get('declaration_of_support_timeout_ms'));
 
-const allowed = /^https:\/\/[a-zA-Z0-9\.\-_]+\/\.well-known\/browserid$/;
+const allowed = /^https:\/\/[a-zA-Z0-9\.\-_]+\/\.well-known\/browserid(\?.*)?$/;
 
 var server = http.createServer(function (req, res) {
   var url = req.url;

lib/primary.js

@@ -191,15 +191,15 @@ var getWellKnown = function (fromDomain, principalDomain, delegates, cb) {
     req = http.get({
       host: httpProxy.host,
       port: httpProxy.port,
-      path: 'https://' + fromDomain + WELL_KNOWN_URL,
+      path: 'https://' + fromDomain + WELL_KNOWN_URL + "?domain=" + principalDomain,
       headers: {
         host: fromDomain
       }
     }, handleResponse);
   } else {
     req = https.get({
       host: fromDomain,
-      path: WELL_KNOWN_URL,
+      path: WELL_KNOWN_URL + "?domain=" + principalDomain,
       agent: false
     }, handleResponse);
   }