v1.16

• [Enhancement] Added exists methods to check whether a row exists or not (by single row key and by array of row keys).
• [Change] persist and delete methods now take T which extends HBRecord<R>, instead of HBRecord<R> directly (change is backward compatible).
• [Change] Removed obsoleted annotation @HBRowKey.
• [Improvement] Maven test dependencies: Upgraded JUnit and Mockito. Removed hadoop-mapreduce-client-core as dependency. Upgraded maven-javadoc-plugin.
• [Change] fetchFieldValues(R[] rowKeys ...) methods now return values of field in the same order as that of array (change is backward compatible).
• [Improvement] Improved javadoc. Improved documentation.