SwiftForum: Simplified navbar username

**What is this?**
This simplifies username display on the navbar, which makes it less cluttered.

![screen shot 2013-08-24 at 8 18 22 pm](https://f.cloud.github.com/assets/777999/1021693/ca1cb64e-0d1d-11e3-8978-d4ee0656f2fa.png)

**Why do we need this?**
The navbar username display at the moment wastes a lot of space that could otherwise be used for other things.

For one, the user will most likely already know what their role is (it doesn't change that frequently) so there's no need to constantly remind them of what their role is. The only people who needs to know what a user's role is are other users, and so it's more appropriate to display their role in the forum threads or in the members-list/roster.

**How would they know what their role is then?**
They can view it at their profile page at any time.

![screen shot 2013-08-24 at 8 29 55 pm](https://f.cloud.github.com/assets/777999/1021703/b63f195e-0d1e-11e3-9d74-52f650ec94d8.png)

Ideally this "Account" card should be a swiftforum reusable element, but at the moment such a thing does not exist yet so I added it directly to the guild site. Also, clicking change will bring them to gravatar.com where they can find out how to change their image.

**Avatar**
As a bonus I've also added the much needed Gravatar display (as seen above) along with an accompanying $user->getAvatar() method to the swiftforum user model.

![screen shot 2013-08-24 at 8 32 38 pm](https://f.cloud.github.com/assets/777999/1021701/a0e39184-0d1e-11e3-9b99-bb8936dc72a1.png)