Http components and APIs now use PSR-7 interfaces
No longer using deprecated Guzzle dependency
Use RFC6455 repo for WebSocket message handling
Remove Hixie76 (refs #201)
Updated deps; React Socket notify client of shutdown
Separated core interfaces into many
Removed initial version support out of handshake negotiator
Moved message parser responsibility to each version
Removed __toString method from MessageInterface as to not confuse message from payload
Support for RFC control frames
Support message concatenation
[BCB] (temporary) WsConnection hard coded to RFC version
Handshake checks for \r\n\r\n anywhere, not just at end of string
Separated handshake negotiation into its own class
`HandshakeNegotiator` deals with Request/Response classes
These changes are geared towards separate responsibility
Refs #29
