fix samples
  * set server-URL in sample script with ARGV  #9
  * set transports websocket in sample

bugfix reconnecting on websocket proxy  #9
  * modify reconnect sleep
  * use default value if ping_interval/ping_timeout not exists  #9
  * detect disconnection by ping-pong timeout #9

bundle update, use websocket-client-simple v0.2.1  #9

bugfix encoding handshake query parameter  #5

add Travis -> Slack notification