- Adds an error check to the riak_kv_keys_fsm:init/3 function to stop
  with an {error, no_type} when a requested bucket type does not exist.
  (https://github.com/basho/riak_kv/issues/875)
- Adds an error check to the bucket lookup in the init function to catch
  scenarios where an undefined bucket type is specified
  (https://github.com/basho/riak_kv/issues/875)
- Modifies riak_kv_buckets_fsm:init/2 to check that the bucket type
  exists.  If it does not, the FSM will stop with a <<"no_type">>
reason.
- Modified the riak_kv_buckets_fsm:init/3 function to directly call
  riak_core_bucket_type:get to defer tricky pattern issue to later
  refactoring
Merge branch 'bugfix/jsb/fix-list-keys-missing-bucket-type' of github.com:basho/riak_kv into bugfix/jsb/fix-list-keys-missing-bucket-type