Fix some OOJS-UI issues

* intializeSelection was removed
* selectItem is replaced by chooseItem, sort of
  (selectItem does not always update the UI, I think?)
* remove old workaround, bug  was fixed upstream

This fixes the download button and unbreaks lots of unittests.
It does not fix the "Loading" text in the embed tab.

Change-Id: Iec7bf9ad5b516001231c7ba46fda962671aaddd8