Need check for 502 error

[dcromster]

I think we need check for this situation:

[error]
api request error: Telegram returned some html instead of json. Body:

<title>502 Bad Gateway</title>

502 Bad Gateway

---

nginx/1.10.0

Error: SyntaxError: Unexpected token < in JSON at position 0
at Object.parse (native)
at IncomingMessage.response.on.e (/home/ubuntu/broader/telegram/node_modules/tiny_request/lib/network.js:70:40)
at emitNone (events.js:91:20)
at IncomingMessage.emit (events.js:185:7)
at endReadableNT (_stream_readable.js:974:12)
at _combinedTickCallback (internal/process/next_tick.js:74:11)
at process._tickCallback (internal/process/next_tick.js:98:9)

[log]
Retry request TelegramApiRequest {
_method: 'getUpdates',
_params: { timeout: 50, offset: 0 },
_multipart: undefined }

[jesusgn90]

It seems like a telegram internal error. Maybe a error handler p
For general purpose will be fine to fix this