MAPG-69 ability to reset signup filled after login attempt

public/static/js/signup.js

@@ -46,4 +46,15 @@
             window.location.replace('/signup/success');
         }, formData);
     };
+
+    var resetSignupButton = document.getElementById('resetSignupButton');
+    if (resetSignupButton) {
+        resetSignupButton.onclick = function () {
+            document.getElementById('loading').style.visibility = 'visible';
+
+            MapGuesser.httpRequest('POST', '/signup/reset', function () {
+                window.location.reload();
+            });
+        };
+    }
 })();