Bitfinex-py-api

- Adds aff_code to WS and Rest submit order functions

- Rework README with new bfx templates
- Generate /docs/rest_v2.md
- Generate /docs/ws_v2.md
- Update comments for doc generation
- Allow only python3 installs in setup.py

- Adds rest.submit_funding_offer
- Adds rest.submit_cancel_funding_offer
- Adds rest.submit_wallet_transfer
- Adds rest.get_wallet_deposit_address
- Adds rest.create_wallet_deposit_address
- Adds rest.submit_wallet_withdraw
- Adds rest.submit_order
- Adds rest.submit_cancel_order
- Adds rest.submit_update_order
- Updates websocket notification event to use Notfication model object

- Added ws event `status_update`
- Added rest function `get_derivative_status`
- Added rest function `get_derivative_statuses`
- Added rest function `set_derivative_collateral`
- Added channel support `status`
- Added create_event_emitter as override in generic_websocket
for custom event emitters

- Removal of camel-casing file naming and git duplicates
i.e bfx.client instead of bfx.Client

- Added change-log and PR/Issue templates