Openpaygo

- Fixes typo in function name
- Improve readme

- Added convenience functions for accessing the current request count and request timestamp
- Improved documentation on how to avoid replay attacks

- Added convenience functions for accessing token count and data timestamp
- Added automatic verification of last request count or timestamp during auth
- Fixed issues in documentation

- Fix token generation issue
- Add support for OpenPAYGO Metrics Request Generation
- Add support for OpenPAYGO Metrics Request Decoding
- Add support for OpenPAYGO Metrics Response Generation

v.2.4.0
What's Changed
* Add deprecation warning by dmohns in https://github.com/EnAccess/OpenPAYGO-Token/pull/30


**Full Changelog**: https://github.com/EnAccess/OpenPAYGO-Token/compare/v.2.3.1...v.2.4.0

v.2.3.1
What's Changed
* Fixed sequential serial number generation by DaniNedo in https://github.com/EnAccess/OpenPAYGO-Token/pull/26
* Update `README` with logo by dmohns in https://github.com/EnAccess/OpenPAYGO-Token/pull/28
* Update PyPI information by dmohns in https://github.com/EnAccess/OpenPAYGO-Token/pull/29


**Full Changelog**: https://github.com/EnAccess/OpenPAYGO-Token/compare/v2.3.0...v.2.3.1