Docker Compose and DB Setup

[maxdemaio]

We'd like to set up a docker-compose file that can spin up a Postgres image, then run our seeder to dump our base dictionaries into it to make dev a bit more seamless. Also, we will update the README.md to explain how it works. The seeder function will be updated for example sentences.

[maxdemaio]

Will test out some ideas later based on TheOpenDictionary/odict#122