Added support for SAML integration in AWS Cognito OAuth2 flow.
With this changes Flask Cognito Auth will now support for the
authentication flow of Outh2 as well as SAML integration in UserPool.
For details of SAML integration :
1. https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-pools-saml-idp.html
2. https://docs.aws.amazon.com/cognito/latest/developerguide/cognito-user-pools-specifying-attribute-mapping.html
Tested:
1. Non federated AWS Cognito User Pool
2. SAML Federated AWS Cognito User Pool with AWS SSO Service.
Changes from 1.0.3 to 1.0.4 in Readme.md file for PyPi link.