Swappable IO layer for MetadataCache.
includes parameterized tests.
Swappable IO layer for ShardState.
stub in a io-datastax module.
Formalize how we run under "dropwizard" mode.

 - inject key configuration values into the Blueflood configuration
 - create config stanzas for riemann and graphite configs
Ensure that we can still run in safely uner the BluefloodServiceStarter.
Merge pull request #292 from gdusbabek/honor_dropwizard_config

Honor dropwizard config
Include custom slf4j logging appender factories in blueflood.  Using these is optional.
Method renames
resolve merge conflicts
Upgrade the http client version in bf-http
Merge pull request #294 from chinmay-gupte/chinmay/upgrade_http_client_version_in_http_module

Upgrade the http client version in bf-http
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
fix merge conflicts