Now when `--help` is called we get all of the subcommands listed too.

Before this patch dm would print out the wall of usage text that would
scroll off the screen in many error cases. This made learning dm hard.
Instead have more compact error output, like kubectl, and only return
non-zero on real errors.

```
$ dm foo ; echo $?
Error: unknown command 'foo' for 'dm'
Run 'dm --help' for usage
1
$ dm deployed-instances; echo $?
No type name supplied
1
$ dm 2> /dev/null; echo $?
0
```

There is more to do to make this tool friendlier but this was
low-hanging.

Use the actual kubernetes object when deleting to ensure it absolutely

Have configurator use the kubernetes_kubectl object

Wire [gs]etcredential to backend

Preserve environment variables executing expansion

Running tests locally fail because $PATH is destroyed

Add support for k8s secrets backed credentials

Add support for k8s secrets backed credentials, remove client support to talking to registry, use server for it. fix a few bugs

Added username and password to credentials in client.

Handle deploy correctly for local files vs. templates

Fix broken links to templates in README

Add support for CredentialProvider 

Add support for CredentialProvider that can be used to specify credentials that should be used for a registry

helm integration

Add registry.ParseType.

ParseType parses a string and returns a *registry.Type. The client
code currently uses this functionality, but it seems like it's better
treated as part of the registry library, rather than as a one-off.

First cut of handling multiple registries with auth.