Fix for #1624

Added in `django-announcements` app which provides simple admin dashboard for adding scheduled announcements. Also styled a basic container to display the announcement on the KA Lite homepage. Feel good about the little app, but not so sure on styling 

Example from current styling:
 
![image](https://f.cloud.github.com/assets/1319950/2265589/f44a10fe-9e83-11e3-85a6-ce6bbd6d0973.png)

Previous examples (text was centered, and in the app there is a place to specify title and content. Above I only show content, below, showing both, with title bolded):
![screenshot from 2014-02-25 17 07 08](https://f.cloud.github.com/assets/1319950/2265619/6c637508-9e84-11e3-8cc7-5eab805ec28f.png)
![screenshot from 2014-02-25 17 01 29](https://f.cloud.github.com/assets/1319950/2265633/87044d06-9e84-11e3-89df-331e29f33208.png)