Hiding the AsyncTaskLoader.waitForLoader method

I introduced this method a couple of weeks ago,
but then we had a chat with Dianne and she made
a good point that rather than having this behavior
on AsyncTaskLoader, we should have it on LoaderManager
and then it will cover all kinds of loaders,
not just the ones inheriting from AsyncTaskLoader.
She suggested that we postpone that work until
after Honeycomb.

Change-Id: I1939956296cddb678791ba652ab5f4a0dd45eea1