docker_compose_install - corrections from original copy

Use python 3, don't hardwire docker version, etc.

roles/docker_compose_install/defaults/main.yml

@@ -0,0 +1,16 @@
+---
+## Installs docker-CE
+# Following guide from here:
+# https://docs.docker.com/install/linux/docker-ce/ubuntu/#set-up-the-repository
+
+# The docker apt repo key uri
+docker_compose_install_apt_key_uri: https://download.docker.com/linux/ubuntu/gpg
+
+# The docker apt repo config line
+docker_compose_install_apt_repo: deb https://download.docker.com/linux/ubuntu {{ansible_lsb.codename}} stable
+
+# This needs to be supplied externally.
+# Get this version from https://github.com/docker/compose/releases/
+# Check compatibility with docker.
+#docker_compose_install_compose_version: 
+