1/ fix incorrect @procted to @private (fixes #280)
2/ make sure data item is always accessible on render item whatever is StoreMap mode (ref ibm-js/deliteful#255)
3/ make sure data/render items always have an ID (fixes ibm-js/deliteful#255)
fix unit tests according to #303
Remove incorrect comment from bf449ab.
It's OK to use delite/place.position(), just want to avoid using dojo's position() method.
HasDropDown: emit events just like DisplayContainer, fixes #301.

Emits:

- delite-display-load
- delite-before-show
- delite-after-show
- delite-before-hide
- delite-after-hide
delite/popup: remove code to call popup's onOpen() method, refs #301