Replace instances of ncsa.illinois.edu with apache.org

- Update package names to be org.apache.daffodil. This breaks API
  backwards compatibility, but only requires a small change to update
  imports and our user base is relatively small right now, so this
  should not affect too many people.
- Add new xml 'daf' namespace for daffodil.apache.org. Backwards
  compatibility is maintained with the previous namespace, and provides
  a pattern for adding new namespace versions for when that may be
  needed. All tests are updated to use the new namespace.
- Some external schema files might reference built-in-formats.xsd in an
  xs:include tag, using the old edu/illinos/ncsa/ directory structure.
  Backwards compatability is maintained by automatically replacing and
  schemaLocations to edu/illinois/ncsa/daffodil/ with
  org/apache/daffodil. A warning id displaying saying the path is
  deprecated.

DAFFODIL-1859