Swappable IO layer for MetadataCache.
includes parameterized tests.
Swappable IO layer for ShardState.
stub in a io-datastax module.
Include custom slf4j logging appender factories in blueflood.  Using these is optional.
Method renames
resolve merge conflicts
populate custom fields when present. fix formatting of example config.
Merge branch 'master' into swappable_io
Merge pull request #287 from gdusbabek/swappable_io

Swappable IO for MetadataCache and ShardState* services
fix test-state test failure.
move appender factories into their own submodule.
update copy right on two poms.
fix merge conflict
Merge pull request #293 from gdusbabek/dropwizard_log_appenders

Include custom slf4j logging appender factories in blueflood
simple lucene discovery index.
ensure a valid no-arg constructor