Make websocket more RFC friendly 

Make websocket more RFC friendly. 
RFC6455,Page 18:
The client MUST validate the server's response as follows:
(...)
2.  If the response lacks an |Upgrade| header field or the |Upgrade|
    header field contains a value that is not an ASCII case-
    insensitive match for the value "websocket", the client MUST
    _Fail the WebSocket Connection_.

3.  If the response lacks a |Connection| header field or the
    |Connection| header field doesn't contain a token that is an
    ASCII case-insensitive match for the value "Upgrade", the client
    MUST _Fail the WebSocket Connection_.
Merge pull request #16 from jcbf/patch-1

Make websocket more RFC friendly ( case insensitive)