Release Notes - Apache Tephra - 0.13.0-incubating

New Features:
[TEPHRA-250]	Create a way to trigger transaction pruning
[TEPHRA-241]	Introduce a way to limit the size of a transaction
[TEPHRA-238]	Support HBase 1.3.x

Improvements:
[TEPHRA-261]	Make TransactionSystemTest.getCommonConfiguration() protected
[TEPHRA-258]	Improve log message for Thrift client connection
[TEPHRA-244]	Invalid tx pruning does not handle deletion of tables well
[TEPHRA-243]	Fix concurrency issues in Transaction log writer; also improve the logging
[TEPHRA-240]	TransactionConflictException should contain the conflicting key and client id
[TEPHRA-231]	Fix the License and the Notice Files for the binary distribution

Bug fixes:
[TEPHRA-260]	Javadoc errors when publishing artifacts
[TEPHRA-253]	TransactionProcessorTest is sometimes flaky
[TEPHRA-242]	Transaction Service sometimes does not shutdown
[TEPHRA-239]	Null pointer exception in TransactionStateCache
[TEPHRA-235]	Flushes and compactions can remove committed data