Now that update_default_page() is available, we can safely replace long SQL insert in setup/install.php with a simple call to update_default_page().
I've added a parameter $note to setup/inc/functions.inc.php#update_default_page() to which we would pass "Upgrading from 1.2 to 1.3"
This commit also adds WikkaConfig page in case of an upgrade.
And some merging of ACLS setting was also performed to simplify the install process.