drag-and-drop metadata not available as tip labels

[joverlee521]

Reported by user on Slack, most likely related to #1668

1. Go to zika build
2. Drag and drop nextstrain_zika_metadata.xlsx
3. See colors added but not tip labels

[joverlee521]

The new metadata is added in place, so there's no Redux state update to trigger the new tip labels to be added

auspice/src/reducers/tree.js

Lines 68 to 70 in dae78e7

	case types.ADD_EXTRA_METADATA:
	// add data into `nodes` in-place, so no redux update will be triggered if you only listen to `nodes`
	addNodeAttrs(state.nodes, action.newNodeAttrs);