allow admin to add stages and change their order

[alexrandaccio]

No description provided.

[whatSocks]

@alexrandaccio whats a stage / how to test this feature?

[alexrandaccio]

@whatSocks Stage is a polymorphic model with 3 subclasses: Delegation, Conversation, and Election (will add a fourth later, called "Custom").

The default "Process" or "Event" has a Delegation, then a Conversation, then an Election.

The point of this PR is to make it possible to create an custom Event.

Some examples:

• Delegation, Conversation, Election
• Delegation, Conversation, Conversation, Election
• Delegation, Election

And so on. Every event is required to begin with a Delegation and end with an Election, however.

[alexrandaccio]

The only way to test it is deploy locally, click "create event", create different kinds of Events and run through them to make sure they are getting set up correctly.

I'm trying to start a test suite, but as always I'm strapped for time. Will get it done though