Add support for data migrations

[NoahJGersh]

Is your feature request related to a problem? Please describe.
Currently, breaking changes invalidate Documents when the data model is updated, and there is no good way to migrate that data on an automatic basis.

Describe the solution you'd like
For areas where breaking changes are introduced between versions, we should support automatic data model migration to ensure that existing Documents aren't invalidated and broken.

Describe alternatives you've considered
Manual modification of the JSON files and manual invocations of migration functions within the console are sufficient to modify actors locally, especially for content modules, but for users that are updating their systems in place, that is a bit too technical (and too poor of a user experience) to really pursue. It is much better to have an automatic process that is supported as the data model, and system as a whole, mature.

Version
0.2.2-0.3.0

Checklist:

• I have searched the existing issues to ensure this feature has not already been requested.