Change user deletion warning to be more explicit.

Issue #4583
- If a user has posts, show the count in the deletion warning.
Tag Cover Images

Closes #4506

Works just like the Post Cover Images (and uses the same component)
Tiny changes to the component ensures that we can reuse it across Ghost
Password change MU

closes #4624
- added user_id to password reset request
- hide old password field
- updated changePassword method to check permissions
- updated changePassword method to work without oldPassword
- fixed bug for errors shown as [Object object]
Merge pull request #4628 from sebgie/issue#4624

Password change MU
Merge pull request #4619 from jaswilli/issue-4583

Change user deletion warning to be more explicit.
Merge pull request #4613 from felixrieseberg/iss4506-2

Tag Cover Images