Enhancement: Add "transcript" field for Generic/Image worktype

[ndroark]

Adding a non-required field labeled Transcript and not mapped to a dc field. Field should be free text, large box, and accept large volume of text.

Help text for field should read "Optional field for entering the written transcript of text contained in object, if that text is not available within the digital object itself (for example, scanned handwritten documents or images of inscribed objects). Do not enter text for OCRed files."