Added 4 new pages and a header

1. Cluster viz -> visualize via D3 the brokers you have in your cluster
2. Topic viz -> visualize via D3 the topics and the active consumers pulling off them
3. Topic list -> a list of the current topics in your broker
4. Topic Detail -> for a given topic see the consumers, more detail can be added to this page later

Also added d3 library include. See screen shots that could be added to wiki page:
http://imgur.com/F4xXARL
http://imgur.com/6eVlTcp
updating based on pull request feedback

-- removed mutable import
-- added loading indicator for dataviz pages
-- improved spacing of topics horizontally
-- added a navbar heading
Merge pull request #4 from CrowdStrike/master

Added 4 new pages and a header