Add helmfile/terraform runner with hierarchical configuration support

[costimuraru]

fixes #43

ops data/env=dev/region=va6/project=ee/cluster=experiments terraform plan
ops data/env=dev/region=va6/project=ee/cluster=experiments helmfile sync

ops data/env=dev/region=va6/project=ee/cluster=experiments config --format json --output-path path/to/file.json

[amuraru]

@costimuraru this looks awesome.
Couple of things we may want in this PR:

1. Add a simple hierarchical configuration example, like in your examples:
   data/env=dev/region=va6/project=myProject/cluster=dev1
2. Add a new section in README.md to explain this new functionality.

Also I would also bump the major version for this tool to 1.0
and add a deprecation warning to old flat file based config?

[costimuraru]

Add a simple hierarchical configuration example, like in your examples: data/env=dev/region=va6/project=myProject/cluster=dev1

Done

Add a new section in README.md to explain this new functionality.

Done

Also I would also bump the major version for this tool to 1.0

Done

and add a deprecation warning to old flat file based config?

I don't know about this one... do we want to impose hierarchical configs on our existing repos (cns)?