MUMUP-1403: Be able to tell users about new stuff

## New Stuff!

Lightweight notification to let users know about new functionality. We talked about different ways to do this, but I just went ahead and implemented an easy way to do this that I think works well. 

There is a small box telling the user about the new feature, and a link to a 'blog' where we can store a list of all of our pushed features.

![image](https://cloud.githubusercontent.com/assets/1919535/5402288/d664dc38-8148-11e4-9771-9fe68203c6a3.png)

The 'blog' it links to:

![image](https://cloud.githubusercontent.com/assets/1919535/5402300/f4611b48-8148-11e4-803d-9affbe505da6.png)

Still stuck on how to hide this when a user wants to get rid of it. We could do this with ngStorage, but then what if we push a new feature soon after that? We would need a way to redisplay the div when we push a new feature. @timlevett, might need help with ngStorage if we decide to use it.


What does getting rid of this `.ui-sortable-placeholder` style have to do with being able to tell users about new stuff?  Is this going to end up being a regression in the drag-n-drop experience?