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.
Should it rather be in default settings, instead of hard coded here ? What if I want to define my version with another key than the default "version", e.g. version_number and use the version key to hold a version name retrieved from Shotgun ?