[Feature] Websocket auto reconnect

[KALRONG]

Hi,

I tried to add the code proposed by samyk in https://github.com/samyk/poisontap/issues/29#issuecomment-263472410 without much luck. I tried changing the first script under backdoor.html with that code.

I think the websocket reconnect is important for cases like in (this is from my tests) windows 10 with chrome where the websocket aborts when you remove the PT and due to the caching issue in chrome you can't perform and f5, if the websocket tried to reconnect I think this should fix the issue.

That said, I must thanks Samyk and everybody posting here, for this incredible tool and with the issues marked help resolve any issues I could find :)