Remove unused node dependency in Cassandra plugin
Fix logging for Hive connectors

Logback was being erroneously included in the plugin zip file by the
Maven assembly plugin. This caused SLF4J or bridged logging to go
into logback and be logged to stdout.
Fix bad import of internal jmxutils class
Update to airlift 0.91 and airbase 22
Update JVM config in deployment instructions

Updated the deployment documentation JVM config instructions to reflect
the Java 8 differences (floatingdecimal patch and PermSize parameters).
Add release notes for 0.71
[maven-release-plugin] prepare release 0.71
[maven-release-plugin] prepare for next development iteration
Replace use of deprecated AsyncHttpClient with HttpClient
Add bytecode generation of serializer for accumulator state
Allow state types to provide their own serializer and state factory
Simplify implementation of aggregation functions

Change AbstractAggregationFunction use to generated state serializer for
serializing intermediates to the wire, and by default for serializing
them in evaluateFinal() (only if the state is a single primitive).

Aggregation functions now optionally implement combineState() to merge
their intermediate state objects, and evaluateFinal() if they need to do
something more than just serializing the current state.
Introduce base class for approximate aggregations

Rewrite approximate AVG to use the new base class
Convert approximate COUNT to new aggregation base class
Convert approximate SUM to new aggregation base class
Remove BlockCursor from new aggregation base classes
Use Metadata instead of MetadataManager
Remove Singleton annotation from class
Use checkType everywhere
Fix warnings