Create separate MigrationHelper class

[HEdingfield]

The migration logic currently lives in GuiConfigController.migrateConfigVersion. We should create a separate (probably static util) class to contain this logic because, as is stands, I don't believe any of the version migration logic works for CLI uses of the tool. Other notes / requirements:

• We may need to add a new CLI flag to handle this, and I think we'll need to make sure it doesn't trigger for version "TEST".
• It should probably also check if going from a future version to a past version and if so, completely bail (we'd need to split on . for the version number then compare biggest number first, middle, then smallest).
• Also test garbage values / words in the version field to make sure the version number comparison fails gracefully.

A stopgap in the meantime if the all of the above isn't immediately doable: add a note saying you can't run this because you're in the CLI and you need to use GUI to migrate the version.