Specify Cluster and Index in Docker Compose File

**Is your feature request related to a problem? Please describe.**
I would like to set default values for the cluster address and index from a docker-compose file.

**Describe the solution you'd like**
The ability to set environment variables for the cluster address and index in a docker-compose file. Also, after firing up the containers and browsing to Dejavu the index(s) are displayed.

**Describe alternatives you've considered**
There's none I could think of that could offer as smooth of an experience on the context of getting a dev environment based on docker containers running.

**Additional context**
None.

Thank you.