Changed serial port option names for cp210x.

+ instead of uppercase style now using _t style.
Now explicitly opening cp210x without auto_recv mode.
Homura is now able to use any of boost protocols for communication.

+ connection and server classes are now generic
  with Protocol template argument.
  Protocol can be any of boost::asio protocol classes that
  support streaming.
+ using aforementioned technique, unix_server has been implemented
  using boost::asio::local::stream_protocol.
+ added base_stream class as an ancestor for data_stream and newly
  created serial_stream. base_stream consists of data_received signal
  and virtual send method.
+ implemented serial_stream class to provide a way of communication with
  serial port using any supported server. serial_stream can be configured
  using opts constructor parameter
+ is a temporary measure, serial_stream is now accessed through dispatcher.
  serial_stream can be obtained via get_stream2 method.
  serial_stream instantiated in dispatcher has stoppark
  terminal parameters (8E1 38400).