Only override the file name for non-local files

[melissalinkert]

Fixes Fiji #498: http://fiji.sc/bugzilla/show_bug.cgi?id=498

[melissalinkert]

To test, verify that opening a file in ImageJ/Fiji and running the macro getInfo("image.filename") returns only the relative path. Also, it's worth double-checking that #9440 hasn't resurfaced as a result.

I've tested both things and they do check out for me.

[melissalinkert]

options.isLocal() returns true when reading directly from a local file on disk (i.e. not from OMERO).

[joshmoore]

Built locally. Both local file via "Plugins > LOCI > Bio-Formats Importer" and "OMERO > Connect to OMERO" look fine.

[joshmoore]

As mentioned offline, the only I can think to add is that once we have the infrastructure in place, it would be good to add a test for this behavior in case isLocal or similar every changes. Perhaps a single list somewhere of all the various things that we could/would eventually need tests for would be useful.