Add signup completion page

app/controllers/signup/eth-account.js

@@ -0,0 +1,13 @@
+import Controller from '@ember/controller';
+import { not, notEmpty } from '@ember/object/computed';
+// import { computed } from '@ember/object';
+
+export default Controller.extend({
+
+  ethAddress: null,
+
+  // TODO address validation
+  isValidEthAccount: notEmpty('ethAddress'),
+  signupButtonDisabled: not('isValidEthAccount')
+
+});