New service API calls to rename or delete a file

Added new DeleteFile and RenameFile methods. The full path to the files must be specified. An example to rename or delete a certain file are:

http://BackendServerIP:6544/Content/RenameFile?FileName=filename&NewFile=newfilename

http://BackendServerIP:6544/Content/DeleteFile?FileName=filename

The commit for PR 35 is also included but can be ignored. Just cherrypick the right commit.