Adding code+settings for changing redirection after publish

This patch introduces a new setting to configure on which page the system redirects after publishing a node in the back office. 

2 settings are introduced : 
RedirectAfterPublish  => to choose the redirect method.
  you can use  "parentNode" (the current method), "node" , "mainNode" , "rootNode" , "uri".

RedirectAfterPublishUri => the uri if the 'uri' method is set.

This patch does not change the  way ezpublish currently redirects. It works on both creation and modification of nodes.