Create a route, controller, and tests for organization invites

[joshsmith]

Problem

Once #518 is done, we'll need to create a route, controller, and tests for organization invites.

Subtasks

• Create the controller tests
• Create the route
• Create the controller (should only be a GET and PUT)

[vishaldeepak]

Shouldn't the controller have three routes?. Get, Put and Create?. Wont we want an OrganizationInvite first be created through a controller action?

[begedin]

@vishaldeepak I would say that yes, create is also necessary, so approach your solution with that in mind.

We should probably also support index, with the option to filter by coalesced ids.

Look to other endpoints for examples on how to do that. UserTaskController, for example