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 #3590 from felixrieseberg/iss3518

Ghost Logo navigation responds correctly to mobile