Add owner role to setup user

closes #3518
- added owner role to user that is added if no user is available
Fix the author context block

fixes #3599

- If the author helper is called as a block (i.e. fn is present) then
  treat it as a with call
Ghost Logo navigation responds correctly to mobile

closes #3522
- Previously, the logo had a href attribute which was manually kept
from executing on mobile. Slow mobile devices that didn’t fully load
the JS would therefore navigate “desktop style”
- The href attribute is now set after the event handler has been loaded, ensuring correct navigation behaviour.
Merge pull request #3600 from ErisDS/author-helper

Fix the author context block
Merge pull request #3596 from sebgie/issue#3518

Add owner role to setup user
Merge pull request #3590 from felixrieseberg/iss3518

Ghost Logo navigation responds correctly to mobile
Swap notification close link for a button

No issue

- Swap out notification <a> close link for <button> (gains a native hover state)