Fixed an issue with traversing ForeignKey primary keys in query filters.

This change does not fix any test case, however, it does allow
one_to_one.tests.OneToOneTests.test_foreign_key to advance further and
later error out on object deletion.
Fixed deletion with ForeignKey primary keys.

This fixes nearly all remaining errors and leaves us with the following:
FAILED (failures=11, errors=1, skipped=416, expected failures=11)