Release Notes - Apache Griffin 0.6.0

** Highlights **
    * Enhancing Griffin's functionality and broadening application scenarios.
    * Fixing some bugs and improving code quality.
    * Adding new features to meet requirements from the Griffin community.


** New Feature
    * [GRIFFIN-256] - Alternatives way to access hive metadata
    * [GRIFFIN-289] - new feature for griffin COMPLETENESS dq type
    * [GRIFFIN-311] - keep null value columns optionally
    * [GRIFFIN-339] - Import griffin tool for debug and run user jobs 


** Improvement
    * [GRIFFIN-240] - [Service] Return JobInstance in response to a call Trigger job by id 
    * [GRIFFIN-247] - Support pluggable sinks
    * [GRIFFIN-253] - How to implement the HA in apache griffin?
    * [GRIFFIN-263] - Use independent logger for griffin
    * [GRIFFIN-264] - Clean up maven dependencies in pom.xml
    * [GRIFFIN-267] - Loggable trait use Scala call by name for lazy evaluation
    * [GRIFFIN-269] - Griffin submit job to livy with Kerberos Authentication
    * [GRIFFIN-273] - Griffin Service with user-defined log4j2 configuration
    * [GRIFFIN-278] - AvroBatchDataConnector handle input is directory
    * [GRIFFIN-279] - Upgrade Spring boot to 2.1.7.RELEASE
    * [GRIFFIN-295] - Limit the memory used by test case
    * [GRIFFIN-298] - Add CompletenessExpr2DQSteps transform test suite
    * [GRIFFIN-299] - Add oracle jdk8 support in travis build phase
    * [GRIFFIN-301] - Update custom data connector to have the same parameters as build-in data connector
    * [GRIFFIN-304] - Remove all traces of different Contexts in favour of SparkSession
    * [GRIFFIN-310] - Format scala code according to scalastyle-config.xml and enable scala code style checking by default
    * [GRIFFIN-312] - Code Style Standardization
    * [GRIFFIN-317] - Define guidelines for Griffin Project Improvement Proposals (GPIP)
    * [GRIFFIN-319] - Deprecate old Data Connectors
    * [GRIFFIN-322] - Add SQL mode for ES connector
    * [GRIFFIN-323] - Refactor configuration for Data Source and Data Source Connector


** Bug
    * [GRIFFIN-266] - [Service] Measure's rules are not always properly sorted
    * [GRIFFIN-270] - Fix wrong hadoop configuration in deploy guide
    * [GRIFFIN-274] - Error: java.lang.NoClassDefFoundError: scala/collection/GenTraversableOnce$class
    * [GRIFFIN-275] - [Measure] Post data to ElasticSearch failed
    * [GRIFFIN-293] - [Service] livy.need.queue=true
    * [GRIFFIN-294] - generate wrong completeness sql
    * [GRIFFIN-296] - Update .travis.yml to specify Maven Memory
    * [GRIFFIN-300] - MySqlDataConnector isn't work
    * [GRIFFIN-306] - FileBasedDataConnector doesn't translate the date in the paths
    * [GRIFFIN-316] - Spark runtime exception cannot be caught while running a dq application
    * [GRIFFIN-318] - Replace all YYYY with yyyy in all user guides and examples
    * [GRIFFIN-321] - visit service web page return 404
    * [GRIFFIN-337] - evaluation rule for uniqueness 
    * [GRIFFIN-329] - Measure unit test cases failed on the condition of no docker image 
    * [GRIFFIN-348] - Change connector schema in data source


** Task
    * [GRIFFIN-271] - Before 0.6.0 milestone release, We need to check and trim current codes against apache griffin dev guide
    * [GRIFFIN-272] - Abort the application if data source fail to load data.
    * [GRIFFIN-276] - Add batch type measure job test case
    * [GRIFFIN-281] - Add custom sink testcase
    * [GRIFFIN-283] - Move sink steps into TransformStep
    * [GRIFFIN-286] - Remove spark-testing-base dependency jar 
    * [GRIFFIN-287] - Use Jackson to parse json data
    * [GRIFFIN-288] - Optimize hdfs sink
    * [GRIFFIN-290] - Fix bug for submitting job to livy
    * [GRIFFIN-291] - Relocate HttpClient code in measure jar using shade plugin
    * [GRIFFIN-297] - GRIFFIN-302 Allow support for additional file based data sources
    * [GRIFFIN-305] - GRIFFIN-303 Standardize Sink Hierarchy
    * [GRIFFIN-315] - GRIFFIN-302 Allow support for JDBC based data connector
    * [GRIFFIN-326] - GRIFFIN-302 New implementation for Elasticsearch Data Connector (Batch)