Create worker subdirectory for worker docker image #3

Is this a BUG REPORT or FEATURE REQUEST?: FEATURE

What happened: Currently there are multiple docker files in the root of the repo. This may be confusing for which docker file creates which image.

What you expected to happen:

1. Create new worker subdir
   • Move Dockerfile.worker and script for the worker image to this directory
2. Move Dockerfile to the controllers subdirectory
3. Update Makefile to reflect these changes