Extract RedisBackedModel.add_attr_reader method
Adjust RedisHash.attr_name to match format add_attr_reader expects
Refactor RedisBackedModel.initialize to set attrs as data structures are created
instead of after.
Refactor internal naming in RedisBackedModel
rename attr_name to be consistent with other 'to_' methods
use let to get consistent with other specs
refactor #initialize tests
remove unneeded test
cleanup variable name
rename #model_name_for_redis to #redis_name
remove unused Commands class