SCHEMA-493. KijiSchema clients should recognize system-2.0 Kiji instances.

issue: https://jira.kiji.org/browse/SCHEMA-493
review: https://review.kiji.org/r/859
SCHEMA-474. Table readers are thread unsafe

 - HBaseKijiTable maintains a pool of HTable instances.
 - Table readers/writers/scanners/pagers acquire HTable instances from the pool.
 - Updated JavaDoc with thread-safety note.

issue: https://jira.kiji.org/browse/SCHEMA-474
review: https://review.kiji.org/r/810
SCHEMA-497. HFileLoader cannot use HBaseKijiTable.getHTable() anymore.

Move HFile bulk-loading logic into HBaseKijiTable.
Symmetric change in KIJIMR-227.

issue: https://jira.kiji.org/browse/SCHEMA-497
review: https://review.kiji.org/r/863
SCHEMA-498. Need a utility class to uniquely identify a KijiSchema client.

Adds a utility class to uniquely identify a JVM.

issue: https://jira.kiji.org/browse/SCHEMA-498
review: https://review.kiji.org/r/870
SCHEMA-499. HBaseKiji owns a (potentially shared) ZooKeeperClient.

- Adds HBaseKiji.getZKClient() with an integration test.
- Implements HBaseKiji.toString()
- Various logging and preconditions cleanup/fixes.

issue: https://jira.kiji.org/browse/SCHEMA-499
review: https://review.kiji.org/r/871
Updates archetype README to be filtered correctly.

Reviewed by: lsheng
SCHEMA-482. Plug ZooKeeper layout notifications in HBaseKijiTable.

issue: https://jira.kiji.org/browse/SCHEMA-482
review: https://review.kiji.org/r/862