BUG: No error message in Insight

[pwalczysko]

During testing of Mark's PR ​https://github.com/openmicroscopy/openmicroscopy/pull/2701#issuecomment-48031250 found out that in case of duplicate fs path, and a consequently failed import, Insight gives no clues as to what is happening.

See details in the comment on the PR. ​https://github.com/openmicroscopy/openmicroscopy/pull/2701#issuecomment-48030851

I think this is valid for a range of situations, not only for this one.

See Mark's comment

here are a few things where something bad happens on the server due to a client action and the client doesn't know how to recognize the exception well and reports something unfriendly instead -- in talking to pwalczysko just now, I wonder if perhaps there should be a general approach of, say, the ServerError? always trying to have a nice message and the clients trying to display that message semi-friendlily ... or something of the sort, anyway. So that for every new server error condition we don't have to do special coding in the clients for a not-horrifying result.

[jburel]

Reading the thread again. The fact that the "View exception" does nothing seems to indicate that nothing meaningful was actually returned.

[jamoore]

Splitting 5.1.4 due to milestone decoupling