Replace support for Google's deprecated Contacts API with Google's People API

This PR builds upon work from @dvratil on adding support for the People API.

As of now, all of a Person object's data field classes are complete. Left to do is:

• Finish the person create job class
• Finish the person delete job class
• Finish the person modify job class
• Finish the person fetch job class
• Implement contact group fetching
• Implement contact group creating
• Implement contact group deleting
• Implement contact group modifying
• Implement proper photo uploading and editing
• Rewrite contact-related tests for people