Implement Engine install and configuration task after machine is created.

[chungers]

We need to implement a consistent way to install the Engine on a host after it's been created. This is the last stage of the processing pipeline that looks like:

1. Use existing or generate new SSH key for a node
2. Create the node using provisioner API and a specified template with optionally provided overrides
3. Install and configure Docker engine on that host
   • Using the login credentials from 1.
   • Possibly different Engine configurations optimized for each platform node / OS version
4. The Engine is now ready and can be added to a Swarm cluster (TBD later)

Note

• We will likely not write new Engine installation scripts. Just invoke the existing Docker installation scripts ==> will look at how Machine does this.
• We can use the same template pattern for engine configurations: e.g. engine_ubuntu14_04 or engine_alpine
• The engine configuration template can be grouped / bundled along with the machine templates so that we have proper association of recommended engine configuration with any Edition-specific params like AMI / image id, OS version, instance types. ==> does this mean we should group configuration templates in folders or via some naming convention of the file names?

[wfarner]

Closing this as InfraKit has evolved quite a bit since the issue was opened. We have basic support for installing Docker Engine in the swarm Flavor plugin, though it may evolve into a separate Docker Flavor plugin.