may ohta

Results 3 issues of may ohta

- build_vocab.py: make sentencepiece options configurable from yaml - add discord_joey.py - fixed #182

There are some naming mismatch in command line args and yaml configs. i.e. `ckpt` in CLI vs. `load_model` in yaml, which might lead to confusion. We should integrate a config...

enhancement
help wanted

- enable DDP in inference - update configs - refactor scripts - fix typo