For 27137 - Set additional fields to ignore when comparing file versions

This adds a configuration setting that can be used to specify additional fields to ignore in file paths when comparing them to find differing versions of the same file.  

For example, if the file name contains the user initials but all users should see these files as a continuous sequence of versions then this setting can be used to achieve this.
That would be a much bigger change as 'version' is used in a lot more places in the code, both in this app and others...  I did consider this but given the likely problems that would ensue I thought it best to leave it like this!