Twenty Fourteen: redo the featured image background pattern with CSS plus minor style adjustments.  Props iamtakashi, fixes #25300. This also fixes #25363, props buffler.
Built from https://develop.svn.wordpress.org/trunk@25610


git-svn-id: http://core.svn.wordpress.org/trunk@25527 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: fix gap beneath header image, props taupecat. Fixes #25404.
Built from https://develop.svn.wordpress.org/trunk@25611


git-svn-id: http://core.svn.wordpress.org/trunk@25528 1a063a9b-81f0-0310-95a4-ce76da25c4cd
Twenty Fourteen: fixes for accent color functionality, props celloexpressions. See #25220.

 * Apply the primary accent color to the current-time indicator for the `mediaelements` players.
 * Fix instances of the custom accent color CSS overriding white or black link colors that should have no text-color change on hover.
 * Remove text color from main navigation hover states for submenus and from main navigation top-level items.
 * Change the background color a bit more on hover for main navigation submenus.
Built from https://develop.svn.wordpress.org/trunk@25612


git-svn-id: http://core.svn.wordpress.org/trunk@25529 1a063a9b-81f0-0310-95a4-ce76da25c4cd