Add highlighting of DOM elements for views

#### What's this PR do?
This adds highlighting of a views `el` DOM element when hovered over or toggled open in the Backbone Debugger view pane.

Currently this just adds and a removes a red CSS box shadow for the highlighting, but I'm completely open to other effects.

I've also included a version bump to `v0.3.0`, as this contains new functionality, but is the same in terms of its user interface.

#### Where should the reviewer start?
The changes made are fairly simple, the only part I'd consider a quite ugly code is using the DOM to store data on the index of the corresponding view element (used in `AppViewsView.js`). Otherwise, it's just adding a couple of new methods and event listeners to achieve the behaviour. If there's a better way for me to achieve this without refactoring the whole project let me know, this code is quite unfamiliar to me.

#### How should this be manually tested?
Open up the debugger on your favourite Backbone app, and use the "Views" tab. You'll notice as you hover over the view links and open/close them, that the corresponding dom element is highlighted in red.

#### Any background context you want to provide?
I work on a large backbone app with a couple of hundred views, it's sometimes very difficult to figure out what view corresponds to which DOM element on the page, my hope is this will help to ease that pain for my team and other Backbone developers.

#### Screenshots:

![screen shot 2014-12-28 at 14 53 01](https://cloud.githubusercontent.com/assets/1911741/5564107/43c28f5e-8ea1-11e4-85b1-53c162a2c82f.png)