This transforms a ConstBufferSequence into a new ConstBufferSequence whose
data is encoded according to the Content transfer encoding rules of RFC2616.
The implementation does not copy any memory.
Many classes required to support type-erasure of handlers and boost::asio
types are now obsolete, so these classes and files are removed:
HTTPClientType, FixedInputBuffer, PeerRole, socket_wrapper,
client_session, basic_url, abstract_socket, buffer_sequence, memory_buffer,
enable_wait_for_async, shared_handler, wrap_handler, streambuf,
ContentBodyBuffer, SSLContext, completion-handler based handshake detectors.
These structural changes are made:
* Some missing includes added to headers
* asio module directory flattened
* streambuf wrapper supports rvalue move
* message class holds a complete HTTP message
* body class holds the HTTP content body
* headers class holds RFC-compliant HTTP headers
* basic_parser provides class interface to joyent's http-parser
* parser class parses into a message object
* Remove unused http get client free function
* unit test for parsing malformed messages
