K8t

- Merge pull request 20 from ClarkSource/codeowners [20](https://github.com/ClarkSource/k8t/pull/20)
- Update cli.py [19](https://github.com/ClarkSource/k8t/pull/19)

Environments would not show properly, this is now fixed.

prefix replacement in environment values has been fixed

allow passing values via environment variables

e.g.


K8T_VALUE_FOOBAR=bar k8t gen


will work for a value `foobar`

replaced all string interpolations with `.format()`

now possible to use `env` to get environment variables

e.g. get variable `FOOBAR` with optional fallback `foo`


{{ env("FOOBAR", "foo") }}