16 more vacuum cleaner manuals added

Links to 16 more vacuum cleaner manuals, parts lists, and service bulletins were added recently.

- Oreck: 4 vacuum cleaner owner's manuals, 6 vacuum cleaner parts manuals, 1 vacuum cleaner service manual, 1 service bulletin
- Viper: 3 vacuum cleaner owner's manuals, 1 vacuum cleaner parts manual