Enable value revisions in field settings

Problem/Motivation

I had the experience of creating a field and not knowing why it wasn't working (or that I had to go to a specific configuration page and then figure out how to use it). All of the configuration happens on the module's settings page.

Proposed resolution

It would feel better if there was a setting available directly on the field settings form for a specific field instance. The form itself would be less confusing (although less suited for bulk configuring), and it would make it a lot easier to remember to configure value revisions for new fields if a setting was available on the field settings form.

User interface changes

Add a checkbox to enable value revisions to the field settings form.