Fixes navigation for Editors on small screen

closes #4707

- Changes Back-link on settings users page to content for editors
Fix modal edge spacing

No issue

The transparent border surrounding modals was being cut off.
This fix uses padding instead of adjusting the left & right valued to create space.
Fix tag mgmt display bugs

- Misaligned header due to back button being in the wrong place in the markup
- Corrected padding on tag delete button
- Updated tag settings input labels for consistency
Merge pull request #4710 from PaulAdamDavis/modal-styling

Fix modal edge spacing
Merge pull request #4711 from JohnONolan/fix-tagmgmt

Fix tag mgmt display bugs
Fix settings back button implementation
Merge pull request #4712 from JohnONolan/fix-backbutton
Merge pull request #4708 from cobbspur/editors

Fixes navigation for Editors on small screen
Merge branch 'master' of https://github.com/TryGhost/Ghost

Conflicts:
	core/client/templates/settings/about.hbs
	core/client/templates/settings/labs.hbs
	core/client/templates/settings/tags.hbs
	core/client/templates/settings/tags/settings-menu.hbs
	core/client/templates/settings/users/index.hbs