More quiz check thoughts

[Carrie Wright]

• I have noticed that if you have a tab after m) C) etc that causes an error for coursera.
• You can have a colon in answers on leanpub but not coursera - maybe we should make that fail the check instead of just a warning
• need a space after the question before the answers or you can get really strange leanpub output despite no errors on our check or on leanpub when rendering