Implement user v2 endpoints #431

User Story

As a user
I'd like to have functional user API endpoints
So that I can create, read, update, and delete users in the system

Acceptance Criteria

• implement GET /v2/users
• implement POST /v2/users
• implement GET /v2/users/{email}
• implement POST /v2/users/{email}
• implement DELETE /v2/users/{email}