mod_http_upload: Don't add "Server" header line

Administrators can add the "Server" header line using the new listener
option "custom_headers", if desired.

src/mod_http_upload.erl

@@ -833,7 +833,6 @@ http_response(Host, Code, ExtraHeaders) ->
       -> {pos_integer(), [{binary(), binary()}], binary()}.
 
 http_response(Host, Code, ExtraHeaders, Body) ->
-    ServerHeader = {<<"Server">>, <<"ejabberd ", (?VERSION)/binary>>},
     CustomHeaders =
 	gen_mod:get_module_opt(Host, ?MODULE, custom_headers,
 			       fun(Headers) ->
@@ -845,10 +844,9 @@ http_response(Host, Code, ExtraHeaders, Body) ->
 			       []),
     Headers = case proplists:is_defined(<<"Content-Type">>, ExtraHeaders) of
 		  true ->
-		      [ServerHeader | ExtraHeaders];
+		      ExtraHeaders;
 		  false ->
-		      [ServerHeader, {<<"Content-Type">>, <<"text/plain">>} |
-		       ExtraHeaders]
+		      [{<<"Content-Type">>, <<"text/plain">>} | ExtraHeaders]
 	      end ++ CustomHeaders,
     {Code, Headers, Body}.