Release v2.3.0

What's Changed

• Bump version to 2.2.0 by @VladimirTaytor in #46
• Fix issue #24: Add batch_send method to SendingApi, add models by @Ihor-Bilous in #47
• Fix issue #42: Add GeneralApi, related models, examples, tests. by @Ihor-Bilous in #48
• Fix issue #41: Add ContactExportsApi, related models, tests and examples by @Ihor-Bilous in #49
• Fix issue #45: Add ContactEventsApi, related models, tests and examples by @Ihor-Bilous in #51

Full Changelog: v2.2.0...v2.3.0