adds ask a librarian functionality

Closes #133 and closes #701 

Has tests for functionality required data attributes in the view, but was conflicted on how to actually test this as it is time dependent on an outside service. I tested it and was able to chat with a librarian.

![screen shot 2014-08-20 at 2 03 27 pm](https://cloud.githubusercontent.com/assets/1656824/3988244/23568800-28ae-11e4-8a8d-4b5b7e991d3b.png)
![screen shot 2014-08-20 at 2 03 38 pm](https://cloud.githubusercontent.com/assets/1656824/3988247/24fdedd8-28ae-11e4-823f-11e7be7f969f.png)
![screen shot 2014-08-20 at 2 03 48 pm](https://cloud.githubusercontent.com/assets/1656824/3988249/27b021e0-28ae-11e4-8b27-7eb2f1512a78.png)

Should clicking link when chat is not available still take people to the ask page on library.stanford.edu?