Change labels in config depending on value of setting

Problem/Motivation

On admin/config/content/node_revision_delete the checkboxes have green or grey backgrounds depending on if they are on or off.
There is also a label 'Enabled' which is the same regardless of status.

Steps to reproduce

Go to config page and change a setting

Proposed resolution

Change labels in config depending on the value of the setting
Also applies to Node Revision Delete settings on Content type edit page

Remaining tasks

User interface changes

As above

API changes

Data model changes