In unit tests, use `wpmu_delete_user()` to delete users when `is_multisite()`.

`wp_delete_user()` doesn't remove the user from the database, which causes all
sorts of problems in certain cases.

Props jeremyfelt.
See [30277], #30017.
Built from https://develop.svn.wordpress.org/trunk@30278


git-svn-id: http://core.svn.wordpress.org/trunk@30278 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.1-alpha-30277';
+$wp_version = '4.1-alpha-30278';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.