[v6r11] new data manager

* New DataManager class to replace the ReplicaManager
* replace the calls to ReplicaManager with calls to DataManager/FileCatalog/StorageElement*
* Reshape a little bit the StorageElement to prepare the change from PFN to LFN
* add getLfnForPfn into StorageElement, and make se.getPfnForLfn and se.getPfnForProtocol compliant with the Successful/Failed return type convention
* remove the use of class method for the dataManager and fileCatalog with instance attributes
add accounting for DataManager.getFile and account for the file size for removal operations (#1331)