Require connected account for adding reimbursement

Just in the UI, so nothing gets reloaded by accident later

app/controllers/budget.js

@@ -1,10 +1,26 @@
 import Controller from '@ember/controller';
 import { inject as service } from '@ember/service';
 import { alias } from '@ember/object/computed';
+import { action } from '@ember/object';
 
 export default class BudgetController extends Controller {
   @service kredits;
+  @service router;
 
   @alias('kredits.reimbursementsUnconfirmed') reimbursementsUnconfirmed;
   @alias('kredits.reimbursementsConfirmed') reimbursementsConfirmed;
+  @alias('kredits.currentUserIsCore') currentUserIsCore;
+
+  @action
+  addReimbursement () {
+    if (!this.kredits.currentUser) {
+      window.alert('You need to connect your RSK account first.');
+      return false;
+    }
+    if (!this.kredits.currentUserIsCore) {
+      window.alert('Only core contributors can submit reimbursements.');
+      return false;
+    }
+    this.router.transitionTo('reimbursements.new');
+  }
 }

app/templates/budget.hbs

@@ -17,7 +17,11 @@
         <header class="with-nav">
           <h2>Proposed Reimbursements</h2>
           <nav>
-            <LinkTo @route="reimbursements.new" @title="Submit a reimbursement" class="button small green">add</LinkTo>
+            <button title="Submit a reimbursement"
+                    class="button small green"
+                    {{on "click" this.addReimbursement}}>
+              add
+            </button>
           </nav>
         </header>
         <div class="content">
@@ -31,7 +35,11 @@
         <header class="with-nav">
           <h2>Confirmed Reimbursements</h2>
           <nav>
-            <LinkTo @route="reimbursements.new" @title="Submit a reimbursement" class="button small green">add</LinkTo>
+            <button title="Submit a reimbursement"
+                    class="button small green"
+                    {{on "click" this.addReimbursement}}>
+              add
+            </button>
           </nav>
         </header>
         <div class="content">