Implement League-Ops Roster Management

[ItsMeBrianD]

Emilio has the concept of a roster offering, which we should implement before releasing version 2, however as a starting point, we should add some basic roster management capabilities.

• The User Manager should have a Franchise field that can be changed
• A Franchise Manager should be added to the Organization Manager that lists the users, and players currently assigned to a franchise. Franchise Leadership / Staff will be implemented in a future issue