Switching the new content admin menu item to respect the same capability as Members List

[kimcoleman]

All Submissions:

• Have you followed the Contributing guideline?
• Does your code follow the WordPress' coding standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Adjusted the capability for the admin + New > Member menu item to respect the same capability we use to check for this on the Members List: edit_users.

[dparker1005]

Should we be using the pmpro_get_edit_member_capability() function here? It looks like this is used elsewhere in the code for the Edit User page.

[kimcoleman]

@dparker1005 I don't think so - we use edit_users here, since adding a member also requires this:

https://github.com/strangerstudios/paid-memberships-pro/blob/dev/adminpages/memberslist.php#L24-L26

But looking at this, perhaps we should change this cap (can be a separate PR just noticed). https://github.com/strangerstudios/paid-memberships-pro/blob/dev/adminpages/memberslist.php#L24-L26. That one could be pmpro_get_edit_member_capability().