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ARROW-1837: [Java][Integration] Fix unsigned round trip integration tests

- Show unsigned values can be round-tripped between java and C++
  in integration tests.  This doesn't fully fix the problem because
  the UInt* APIs are mostly wrong because they can't represent the
  full range of unsigned values (return types are all too small
  because java only has signed types).

- While I was at it, I fixed the issue with no batches.

Author: Micah Kornfield <emkornfield@gmail.com>
Author: emkornfield <emkornfield@gmail.com>

Closes #4432 from emkornfield/fix_integration_tests and squashes the following commits:

226c4af0 <Micah Kornfield> fixes
27e47383 <emkornfield> Add missing comma to integration test
d8ad3d85 <Micah Kornfield> Address PR feedback
a6a23e9d <Micah Kornfield> ARROW-1837:  Fix unsigned round trip integration tests