Auto merge of #1759 - smarnach:manage-owners-yanked, r=carols10cents

Show right-hand column for yanked versions to crate owners.

Fixes #1660.

Without this change, the page for a yanked version looks like this:

![image](https://user-images.githubusercontent.com/249196/58944345-ec823d00-8781-11e9-9322-019250a6fb1d.png)

With this change applied, crate owners see this page instead:

![image](https://user-images.githubusercontent.com/249196/58944390-0de32900-8782-11e9-9c58-ac649c9c23c0.png)

Author: bors

app/controllers/crate/version.js

@@ -32,6 +32,11 @@ export default Controller.extend({
     isOwner: computed('crate.owner_user', 'session.currentUser.id', function() {
         return this.get('crate.owner_user').findBy('id', this.get('session.currentUser.id'));
     }),
+    notYankedOrIsOwner: computed('model', 'crate.owner_user', 'session.currentUser.id', function() {
+        return (
+            !this.get('model').yanked || this.get('crate.owner_user').findBy('id', this.get('session.currentUser.id'))
+        );
+    }),
 
     sortedVersions: readOnly('crate.versions'),