Twenty Fourteen: allow pages to have featured images, props iamtakashi. Fixes #25325.

Built from https://develop.svn.wordpress.org/trunk@25735


git-svn-id: http://core.svn.wordpress.org/trunk@25648 1a063a9b-81f0-0310-95a4-ce76da25c4cd
 Twenty Fourteen: fill browser height to 100% for views with short content. Accounts for footer widgets, in which case the height isn't set to 100% so that the widgets remain visible. Props wycks and taupecat, fixes #25389.

Built from https://develop.svn.wordpress.org/trunk@25736


git-svn-id: http://core.svn.wordpress.org/trunk@25649 1a063a9b-81f0-0310-95a4-ce76da25c4cd