Feature request: Option to disable for specific roles and/or content types

Problem/Motivation

Currently, when the revision log field is empty, the default is used always.

The ability to disable this activity by content type would be valuable in cases where the content type is non-complex or not particularly sensitive. For example, if the content type has only one field.

The ability disable this activity by role would be valuable in cases where the content editor is a low privileged role and does not have access to the Revision Log box. This happens when the user doesn't have any creation or revision management privileges, just limited edit privileges.

Proposed resolution

The request is to add configuration items to disable for content types or roles.

Since the module is called "Revision Log Default," I figured that enabling should mean the default behavior is all of it being ON. That's why I leaned to the exclude model.