Twenty Thirteen: center footer text in RTL, props yoavf. Fixes #24110.

git-svn-id: http://core.svn.wordpress.org/trunk@24012 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Twelve: remove zero-width spaces in CSS value, props SergeyBiryukov. Closes #23790.

git-svn-id: http://core.svn.wordpress.org/trunk@24013 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Twelve: add back missing space in CSS value, removed in r24013. See #23790.

git-svn-id: http://core.svn.wordpress.org/trunk@24014 1a063a9b-81f0-0310-95a4-ce76da25c4cd