First pass of user admin. Network admin and screen cleanups. see #14696

git-svn-id: https://develop.svn.wordpress.org/trunk@15746 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/capabilities.php

@@ -737,6 +737,7 @@ class WP_User {
 
 		// Must have ALL requested caps
 		$capabilities = apply_filters( 'user_has_cap', $this->allcaps, $caps, $args );
+		$capabilities['exist'] = true; // Everyone is allowed to exist
 		foreach ( (array) $caps as $cap ) {
 			//echo "Checking cap $cap<br />";
 			if ( empty( $capabilities[$cap] ) || !$capabilities[$cap] )