Install & Upgrade Logo Not Retina Ready

[kopepasah]

The WordPress logo on the install (install.php) and upgrade (upgrade.php) pages still reference the standard WordPress logo instead of the Retina ready 2x logo for Retina devices.

Included is a patch that adheres to the WordPress login page's method of rendering a Retina ready WordPress logo for the WordPress install and upgrade pages.

22375.diff​:

• Removes _e() from the beginning of install.php, where i18n functions are not available yet.
• Makes the WordPress.org URL translatable, like the one we already use in several places:
  http://core.trac.wordpress.org/browser/tags/3.4.2/wp-login.php#L78
  http://core.trac.wordpress.org/browser/tags/3.4.2/wp-includes/admin-bar.php#L99
  http://core.trac.wordpress.org/browser/tags/3.4.2/wp-includes/default-widgets.php#L318
• Adds escaping for the title attribute (not sure if the attribute itself is necessary though).
• Handles the same logo in setup-config.php.

The same logo is also used in wp-admin/maint/repair.php and wp-admin/network/sites.php (not addressed in the patch).

This looks good. A few notes, we rarely bother to translate WordPress, and the title doesn't seem necessary

attachment:22375_3.diff​

• Removes the title from the anchors.
• Adds the same logo in wp-admin/maint/repair.php and wp-admin/network/sites.php.

In 22419:

Use retina logo in install, upgrade, setup-config, repair, and confirmation screens.

Props kopepasah, SergeyBiryukov
fixes #22375