wip-192: Refactored and renamed AuthConf to ConnectionConfigurator

The changes introduced with this fix include:
- Renaming AuthConf to ConnectionConfigurator and replacing method authProvider: AuthProvider with configureClusterBuilder(Cluster.Builder): Cluster.Builder, which may set arbitrary connection options on the cluster builder
- Renaming NoAuthConf, PasswordAuthConf, AuthConfFactory, DefaultAuthConfFactory to NoAuthConfigurator, PasswordAuthConfigurator, ConnectionConfiguratorFactory and DefaultConnConfFactory respectively and adjusting them to the new interface
- Adjusting CassandraConnector and CassandraConnectionConf to the new interface
- Updated tests and docs

Fixes #192