Add net-ssh-gateway gem
Simplify Hansolo module into configuration store
Add a base command class

Manages parsing command line options and reading in Hanfile.  Extract
behavior that should be override-able into a module so it can be
overridden by another module, included after DefaultBehavior.
Add `hansolo-ssh`

Picks one of the targets and SSHs into it.  Supports SSH via a bastion.
Extract `hansolo-databag`
Add `hansolo` command class
Add AWS provider

Overrides behavior defined in `default` provider to support discovery of
targets/bastion on EC2 and storing data bags on S3.
Update README
Remove callback attributes
Extract `bucket_name` into a `Hansolo` attribute

Scope all data bags for an application with the application name instead
of creating a bucket for each application.
Setup yardoc
Only set `#bastion` if `Hansolo.gateway` is set
Memoize `#hosts`
Documentation
Refactor