Appr

- Fix 83: Implements .helmignore
- Fix 80: Updated the `appr plugins install helm` to download either windows or linux tarball
- Fix 67: Preserve Helm dependency options
- `appr helm dep` exits without error if `requirements.yaml` isn't present

- Fix 72: MacOS build
- Fix 73: Exit with the same error-code than Helm

- Add login/creds per namespaces / repo

shell
login for the domain
$ appr login quay.io
login for the namespace
$ appr login quay.io/ns1
login for the a repo
$ appr login quay.io/ns1/repo1


- Update helm plugin to expose all top-level commands under `appr helm`
to eliminate the shell script workaround.

- Fix json output on error

- Auto-select media-type when possible, `--media-type` is now optional

- Introduce client-side deployments handling multiple formats:
- [ ] [Helm](https://github.com/kubernetes/helm)
- [x] [appr](https://github.com/coreos/kpm)
- [ ] Plain kubernetes configuration

- Add jsonnet support for future integration with [ksonnet](https://github.com/ksonnet/ksonnet-lib)

- New commands:

shell
Resolve a jsonnet file, with a set of nativeExtension available
appr jsonnet FILE

Client side deployment command
appr deploy quay.io/ant31/kube-lego --namespace kube-lego

- Add options to allow unverified certs or custom CA.
shell
-k, --insecure turn off verification of the https certificate
--cacert [CACERT] CA certificate to verify peer against (SSL)