SCHEMA-445. HBaseDataRequestAdapter generates improper Get request with KeyOnlyFilter when paging

- Updates TestHBaseDataRequestAdapter to trigger the bug.
- Updates test layout to use a formatted entity ID..
- Adds HBaseKijiRowData.toString() debug string.
- Fixes the behavior of HBaseDataRequestAdapter:
Uses FirstKeyOnlyFilter instead of KeyOnlyFilter.

issue: https://jira.kiji.org/browse/SCHEMA-445
review: https://review.kiji.org/r/743