Improve UNSUPPORTED_DATA_TYPE message in JSON output object

[jrobble]

End users find this message confusing:

"code": "UNSUPPORTED_DATA_TYPE",
                  "message": "The detection component does not support detection data type of UNKNOWN"

This happened when trying to process a plain text file. Users assume that OpenMPF knows what a text file is, considering that at least one component supports that MIME type.

To improve this message, mention the MIME type:

"The detection component does not support detection data type of text/plain."

[brosenberg42]

I think we should provide more information in UNKNOWN/GENERIC case. If someone sees "The detection component does not support detection data type of application/msword." They may try to convert it to PDF, get an error, then try to convert to OpenOffice, etc.

I think we should make it say something like "The detection component does not support detection data type of GENERIC. The mime type was detected to be text/plain, which was classified as GENERIC because it isn't an image, video, or audio file. The component does not support any GENERIC media."