Merge pull request #2 from zackurben/dev

Adding unit tests and updating API urls
[#71587328] Adding support for multiple environments. Added dev/prod urls and guzzle options for each environment.
Merge branch 'master' of https://github.com/AllPlayers/service-webhooks into dev
[#71587328] Updating authentication URL to fix broken test. Updating client objects to be explicitly defined for each respective environment in each partner-mapping method.