Dataset (and jpeg/text two up) item viewer prep and refactoring

- Added four new item viewers, completed all mapping to database and metadata, etc..
   - Dataset codebook viewer
   - Dataset reports viewer
   - Dataset view data viewer
   - Page image/page text two-up display
- New sql script included for adding these to the database item viewer types tables
- General refactoring - renamed some common parameters that affected nearly all the metadata element templates