N°2013 Setup : fix crash on setting readonly mode if initial DB info were wrong

Same as 15d3201a, but this error happened before compilation, when setting read only mode.
As before this is another fix for #351.

This fix introduces the new method \WizardController::GetParamForConfigArray
I replaced existing duplicate code with a call to this new generic method.

setup/parameters.class.inc.php

@@ -22,7 +22,7 @@ abstract class Parameters
 	}
 
 	/**
-	 * @return array to use with {@see Config::UpdateFromParams}
+	 * @return array Allow to update config using {@see Config::UpdateFromParams()}
 	 */
 	public function GetParamForConfigArray()
 	{