Initial commit of BlogEntry Panel

I've added in a 'registered' function to the DashboardPanel.php. By default all panels return true but in this instance I only want this panel to appear in the panel list if the BlogEntry class exists.

You may want to check this over and there could well be a better way to do it. This could do with some tiding, particularly in the notifications following a post but...  release early, release often. 

![Screen Shot 2013-02-07 at 9 15 12 PM](https://f.cloud.github.com/assets/188229/135276/b43ec382-7117-11e2-81ad-78938005086f.png)