parallelising RSpec test

circle.yml

machine:
    pre:
      - curl -sSL https://s3.amazonaws.com/circle-downloads/install-circleci-docker.sh | bash -s -- 1.10.0
    services:
        - docker
dependencies:
  override:
    - sudo pip install --upgrade docker-compose
    - docker build --rm=false -t project/image:ci .
database:
  override:
    - echo "Skipping DB section."
test:
  override:
    - docker-compose up
    - docker-compose ps -q | xargs docker inspect -f '{{ .State.ExitCode }}' | grep -v 0 | wc -l | tr -d ' '