This allows a list of drop-ins for a unit to be declared inline within a
cloud-config. For example:
#cloud-config
coreos:
units:
- name: docker.service
drop-ins:
- name: 50-insecure-registry.conf
content: |
[Service]
Environment=DOCKER_OPTS='--insecure-registry="10.0.1.0/24"'
