[FEATURE] Support passing parameters to the reset method.

[burtenshaw]

It would be great to be able to provide a parameter to the /reset route to tell how you want to reset your env. Examples I have in mind are:

• a seed (if randomly generated)
• for Atari env, the name of the game you want to play
• for Poker, the number of players

These would be more convenient than restarting the server. In practice I think we should enforce all parameters to be optional, so the current behavior reset still works.

[rycerzes]

@burtenshaw PR #217 adds support for parameterized step/reset

[Darktex]

This makes sense to me. We can make params as part of the general spec, and the specific envs can implement their own params