Fixed table.plain css

Looked to be LESS formatted CSS that hadn't been compiled. Just replaced with the equivalent compiled CSS.
Auto height for img in post-content
Merge pull request #28 from JoeBonham/patch-1

Replaced table.plain LESS with equivalent CSS
Merge pull request #31 from alicoding/master

Auto height for img in post-content
Merge pull request #1 from TryGhost/master

Update from TryGhost:master