Made /wol a POST request instead of a GET

Since it does modify state.

* Also fixed a bug where ping did sometimes still write to the
response.

static/main.js

@@ -69,8 +69,11 @@ var request_wol = function (host) {
         }
     });
 
-    request.open("GET", "wol/" + host.mac);
-    request.send();
+    var params = "mac=" + host.mac;
+
+    request.open("POST", "wol", true);
+    request.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
+    request.send(params);
 
     setTimeout(function () {
         request_refresh(host);