Inveon: ignore the absolute path to the image file (rebased onto dev_5_0)



This is the same as gh-1168 but rebased onto dev_5_0.

----

This prevents an exception from being thrown when the absolute path is
stored, but does not match the true absolute path to the image file.

To test, verify that the dataset in ```data_repo/from_skyking/inveon/samples``` imports with the PR included; without this PR included, the same dataset should throw an exception due to the image file not being found.

                    
```replaceAll``` in the first line is just habit; ```replace``` in the second line is necessary for dealing with ```\``` characters.  Given that this pattern exists all over the readers and this is a rebase, can I push documentation (and maybe turning this into a utility method) to a separate PR?