Replace massive loading image with new zendesk loader

The circle loader is a little overkill for an app don't you think. How about this:

![screen shot 2013-04-30 at 9 04 16 am](https://f.cloud.github.com/assets/562605/441695/b9cf3eee-b122-11e2-8884-9f4faa78e3cc.png)

cc @jakeisonline @danielbreves @eboyle