Ensure special validators are present after a BookData object is cleared

The clear method removes validators by default; this was causing imports
to fail.
5.0 Beta 4 release changes
Description and translation updates
Added owner to task wrapper so tasks can check if queue is terminating
Check if GetList queue is terminating, and discard resources if so

This is *not* a complete fix for the Android 2.1 statement problem, but
it reduces the impact.

There is still a chance that a queue may have finish() called after a
task has completed but before onFinish() is run. Which is why we need
some kind of onTerminate() handler, or a flag to onFinish().
5.0 Beta 5 release changes
Merge pull request #466 from Grunthos/master

5.0 Beta 5