fix(avatars): load profile image on settings and sign in pages if available

Fixes #1727

Also fixes #1722.
Closes #1544.
Closes #1613.
This seems to have a bit more error checking than app/scripts/lib/local-storage.js#L21:

```js
+  Storage.prototype.get = function (key) {
+    return JSON.parse(this._backend.getItem(fullKey(key)));
+  };
```

Not sure if we want to do more error checking in the other file, or how `JSON.parse()` will behave if it cant find the item (ie: return `undefined` anyways and the extra check isn't needed).