improve connection handling

[aheckmann]

buffer until connected
once disconnected
  option 1: fail fast
    just return errors
  option 2: buffer
    buffer cmds until reconnection
    if reconnection takes > optional timeout
      fail buffered cmds, keep returning errors until reconnection

current driver behavior:
  no buffering until connected
   auto_reconnect buffers cmds when disconnected until reconnection
   if auto_reconnect = false
      no cmds are buffered, errors are returned
      but you must reconnect manually ...
      HOWEVER there isn't a graceful way to do this yet. need to make changes to driver