First Commit. Feb 27, 2014 @dakuo

Functions completed:
1. Download revision documents to the server.
2. Analyze revision diff to generate the historyflow.json intermediate
data structure.
3. Visualize the result using D3.js at front-end in index.html
4. Filter revisions based on revision index to show cerntern revisions
visualization.
5. Retrieve text trunk content based on the user's request (click on the
content).

Funtion TO-DO List:
1. Detect updates. (Back-end).
2. Save the SVG as an Image for users to export the diagram. (partially
working)
3. Deploy the system into a deployment server (now using Jetty; might
think about using Tomcat.)
Forgot to submit the four global configuration files.