Kyunghwan Kim

Add grouping depends on category when log by wandb. - Agent - integration test

 

I think this kind of flag name is better than previous flag. - `--load-from` -> `--ckpt-path` If you have other ideas, please leave comments below.

A2C algorithm is implemented for continuous environment like Lunarlander-continuous now. We should implement A2C for discrete environment because its performance can be better in discrete env.

We should change Mujoco env to [Pybullet-gym](https://github.com/benelot/pybullet-gym) env because Mujoco license is expired. Pybullet-gym has a lot of continuous action environments include reacher, half-cheetah.