SCHEMA-388. KijiRowScanner should handle underlying HBase ScannerTimeoutException.

- Extends Kiji row scanner options with:
  - RowCaching : # of rows to fetch per RPC to the region server.
  - ReopenScannerOnTimeout : automatically handle ScannerTimeoutException by
    re-opening the HBase scanner on timeout.

There is an integration test to validate these features.
However, the test is not included in this change:
it requires a specific configuration on the HBase cluster,
namely setting hbase.regionserver.scanner.period to a low value.
See SCHEMA-393 and FAKEHBASE-9.

issue: https://jira.kiji.org/browse/SCHEMA-388
review: https://review.kiji.org/r/600