Services refactor, remove hardcoded smart contract code

Removed all the hardcoded services to make the code cleaner. This is a backwards incompatible change since the current methods to access smart contract functions weren't PEP8 standard, didn't comply with SRP nor DRY either. IMPORTANT: This makes the new library incompatible backwards, check the examples to see how to implement it.

Presentation registry fixes

v0.4.0

Updated in pyproject

Fix credential registry operations

• Fix credential registry operations to use the correct smart contract address when delegated

Added homepage url and CHANGELOG

v0.2.0

Updated CHANGELOG