Swappable IO layer for MetadataCache.
includes parameterized tests.
Swappable IO layer for ShardState.
stub in a io-datastax module.
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
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.
fix merge conflict