Twenty Eleven fixes, props matveb - see #17198

- Add padding to the menu when the search input is in menu bar
- Improve search input behavior when located in menu bar (also props ocean90)
- i18n for post formats headings (also props nickbohle)
- Small style fix for images

git-svn-id: https://core.svn.wordpress.org/trunk@17845 1a063a9b-81f0-0310-95a4-ce76da25c4cd