Improve the table header in the Node Revision Delete Administration Page

Problem/Motivation

The header is defined as:

  // List tracked content types.
  $headers = array(
    'Content Type',
    'Machine Name',
    'Revisions to Keep',
    'Candidate nodes',
    ' ',
  );

But Drupal use the strings as '[Upper]aaaaa [lower]bbbbb.

Proposed resolution

Change the strings to, and change the last header to 'Operations'

  // List tracked content types.
  $headers = array(
    'Content type',
    'Machine name',
    'Revisions to keep',
    'Candidate nodes',
    'Operations',
  );

Remaining tasks

None.

User interface changes

In the Node Revision Delete Administration Page (admin/config/content/node_revision_delete) you will see the table header like this:

API changes

None.

Data model changes

None.