Bitfinex-api-py

- fixes dep issues

- [Upgrade project's 'Development Status' to '5 - Production/Stable'](https://github.com/bitfinexcom/bitfinex-api-py/commit/ba76447c414daea88468aa33a5e60f9faaaecb68)
- [Remove all references to beta versions in README.md](https://github.com/bitfinexcom/bitfinex-api-py/commit/089e193780b41a4b60976cce91a21c369e5ae027)
- [Handle unexpected errors in HTTP requests (bfxapi.rest._interface)](https://github.com/bitfinexcom/bitfinex-api-py/commit/65318beee970c0a753162b82b8ce374ef723e6ce)

- Fix low latency bug in public method BfxWebSocketBucket::start
- Fix bug in order_book.py and raw_order_book.py examples

This fixes a minor bug in method BfxWebSocketClient::resubscribe.
**All bitfinex-api-py v3-beta's users should upgrade their projects.**

> **DISCLAIMER:** \
Production use of v3.0.0b4 (and all future beta versions) is HIGHLY discouraged. \
Beta versions should not be used in applications which require user authentication. \
Provide your API-KEY/API-SECRET, and manage your account and funds at your own risk.

* type hinting support for all API's components.
* a faster, lighter and more secure websocket client.
* several bug fixes for both http and wss interfaces.
* **...and much more!**

> **DISCLAIMER:** \
Production use of v3.0.0b3 (and all future beta versions) is HIGHLY discouraged. \
Beta versions should not be used in applications which require user authentication. \
Provide your API-KEY/API-SECRET, and manage your account and funds at your own risk.

- readme update
- refactoring improvements