Fix table editor to respect 'orientation' trait

This PR resolves #170 and now respects `factory.orientation` trait if set, but otherwise defaults to `QtCore.Qt.Horizontal`.
Fix default 'orientation' to Vertical if not set

Just inverting the default in the previous commit's fix (SHA: e6d42dd681c7a559f5e30038025279a974711fb9). Vertical by default now, Horizontal if set in `factory.orientation`.
Update CHANGES.txt
Merge pull request #171 from jordanweaver/fix-qt-table-editor-orientation-trait

Fix table editor to respect 'orientation' trait