Add Evaluation section

[jlouvel]

Similar to chapter 6 in Fielding's dissertation:
http://roy.gbiv.com/pubs/dissertation/evaluation.htm

• Standardizing the Programmable Web
• Web API applied to URI
• Web API applied to HTTP (versions 1.1, 2.0)
• Web API applied to HTML (version 5, AJAX, Server-Sent Events, WebSocket mismatch, etc.)
• Architectural Lessons