rename EP: REXSEO_POST_INIT -> REXSEO_INCLUDED
version bump -> 1.5.2
Merge branch 'refs/heads/nightly'

Conflicts:
	classes/class.github_connect.inc.php
	classes/class.rexseo_meta.inc.php
	classes/class.rexseo_rewrite.inc.php
	classes/class.rexseo_robots.inc.php
	classes/class.rexseo_select.inc.php
	classes/class.rexseo_sitemap.inc.php
	config.inc.php
	controller.inc.php
	files/backend.css
	functions/function.rexseo_helpers.inc.php
	help.inc.php
	install.inc.php
	install/backup/backup/addons/rexseo/config.inc.php
	install/files/.htaccess
	install/files/redaxo/.htaccess
	pages/github_api.inc.php
	pages/help.inc.php
	pages/index.inc.php
	pages/settings.inc.php
	uninstall.inc.php
version bump -> 1.5.3
check valid addon folder name at install..
make addon folder check generic (aka copy & paste-able..)
now.. really.. generic.. ;)