Bug 19648: Revise marc21_field_007.xml

Bug 19648: Revise marc21_field_007.xml

- Removes some doubled up entries
- Fixes some whitespace issues
- Adds some missing entries, for example:
    007, nonprojected graphic, secondary support material a-c

To test:
  - Verify that the 007 cataloging plugin works correctly and
    matches standard:
    http://www.loc.gov/marc/bibliographic/bd007k.html

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>