Merge PR #1125 branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/10972] Drop user deletion.
  [ticket/10972] Tweak user addition.
  [ticket/10972] Add destroy method to mock cache.
  [ticket/10972] Add mock null cache.
  [ticket/10972] Backport get_db from develop.
  [ticket/10972] Added explicit checks for creating duplicate users.
  [ticket/10972] Moved tests into appropriate places and added comments
  [ticket/10972] Added methods for creating and deleting basic users

Conflicts:
	tests/mock/cache.php
	tests/test_framework/phpbb_functional_test_case.php

tests/mock/null_cache.php

@@ -0,0 +1,47 @@
+<?php
+/**
+*
+* @package testing
+* @copyright (c) 2012 phpBB Group
+* @license http://opensource.org/licenses/gpl-2.0.php GNU General Public License v2
+*
+*/
+
+class phpbb_mock_null_cache
+{
+	public function __construct()
+	{
+	}
+
+	public function get($var_name)
+	{
+		return false;
+	}
+
+	public function put($var_name, $var, $ttl = 0)
+	{
+	}
+
+	public function destroy($var_name, $table = '')
+	{
+	}
+
+	public function obtain_bots()
+	{
+		return array();
+	}
+
+	public function obtain_word_list()
+	{
+		return array();
+	}
+
+	public function set_bots($bots)
+	{
+	}
+
+	public function sql_exists($query_id)
+	{
+		return false;
+	}
+}