http: handle multiple Proxy-Authenticate values

Just as the 'WWW-Authenticate' HTTP header the 'Proxy-Authenticate' header might
be received several times as well. Currently only one value is preserved. This
change allows to receive multiple values concatenated by space and comma.

lib/http.js

@@ -401,6 +401,7 @@ IncomingMessage.prototype._addHeaderLine = function(field, value) {
     case 'pragma':
     case 'link':
     case 'www-authenticate':
+    case 'proxy-authenticate':
     case 'sec-websocket-extensions':
     case 'sec-websocket-protocol':
       if (field in dest) {

test/simple/test-http-server-multiheaders.js

@@ -31,6 +31,7 @@ var srv = http.createServer(function(req, res) {
   assert.equal(req.headers.accept, 'abc, def, ghijklmnopqrst');
   assert.equal(req.headers.host, 'foo');
   assert.equal(req.headers['www-authenticate'], 'foo, bar, baz');
+  assert.equal(req.headers['proxy-authenticate'], 'foo, bar, baz');
   assert.equal(req.headers['x-foo'], 'bingo');
   assert.equal(req.headers['x-bar'], 'banjo, bango');
   assert.equal(req.headers['sec-websocket-protocol'], 'chat, share');
@@ -57,6 +58,9 @@ srv.listen(common.PORT, function() {
       ['www-authenticate', 'foo'],
       ['WWW-Authenticate', 'bar'],
       ['WWW-AUTHENTICATE', 'baz'],
+      ['proxy-authenticate','foo'],
+      ['Proxy-Authenticate','bar'],
+      ['PROXY-AUTHENTICATE','baz'],
       ['x-foo', 'bingo'],
       ['x-bar', 'banjo'],
       ['x-bar', 'bango'],