more tests
test by openaire identifiers, multiple dois, multiple author identifier, multiple provider identifiers.
Refactoring
Generating today's date.
using sygma schema 2.1 for validation
Testing max page size
tests for the sygma model
Tests for list of available parameters
tests for the Openaire format publications API
ignore sygma test for now
Classes to test the HTTP API of OpenAIRE+
Created basic project structure