Saves the refering URL to return to it

Sets the refering url in a session key to be used by Croogo::redirect..
after redirection it is cleared.

Refs:
Cherrypicked from: ecoreng/croogo@filter-saving (c5fa9a41f3b67f)
http://article.gmane.org/gmane.comp.cms.croogo/1

Signed-off-by: Rachman Chavik <rchavik@xintesa.com>
Minor CS fixes + docblock updates
Merge branch '1.6-filter-saving' into 1.6