Set layout to null to suppress warning

Not applied in 0f1660437beba58cd2974f07270b19305b9bbfd9.
Merge pull request #1629 from yous/patch-layout

Set layout to null to suppress warning
Merge remote-tracking branch 'upstream/master' into source
Squashed '.themes/whitespace/' changes from 7b2e05b..1385a27

1385a27 Merge pull request #53 from yous/patch-octopress-compatible
eb47605 Merge pull request #51 from yous/patch-googleplus-user
970cfce Merge pull request #52 from yous/patch-mathjax
ca29e4f Make theme be compatible with latest Octopress
e243071 Use double quotes in HTML
4d35cd9 Join MathJax script lines
ff178af Use HTTPS when on HTTPS site
9460ca9 Simplify code using `googleplus_user` as author
f9c5378 Fix indentation

git-subtree-dir: .themes/whitespace
git-subtree-split: 1385a27a823fa95d01f1acde2cd396cb9b1f19a5
Merge commit 'c462fd3754c87c69e83f0e8588f5f622cc457c76' into source
Apply whitespace theme

1385a27a823fa95d01f1acde2cd396cb9b1f19a5