Full compliance with HTTP RFC nomenclature

HTTP clients should be compliant with the nomenclature established by the HTTP RFC [1, 2]. This issue addresses the verification of:
- Messages: Request, Response
- Headers: Field Name, Field Value
- Body: Message body vs Entity Body
- URI/URL
- etc...

[1] http://www.w3.org/Protocols/rfc2616/rfc2616.html
[2] http://www.w3.org/Protocols/rfc2616/rfc2616-sec1.html#sec1.3
