Modal spacing & warning colour

Closes #4583

- Adds a `.red` class (used to make the post count red)
- Adds a little spacing under the modal header to things arent bunched up
Autosave for whitespace-only titles

closes #4625
- trim white space form `titleScratch` to enable autosave for
whitespace-only titles
Merge pull request #4632 from PaulAdamDavis/modal-colour-spacing

Modal spacing & warning colour
Merge pull request #4635 from ikhattab/fix-autosave-whitespace-title

Autosave for whitespace-only titles
Merge branch 'master' of https://github.com/TryGhost/Ghost