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

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

Add support for short github.com types. Refactor manager/manager/types to common/types and reuse them rather than redefine them.

Add support for short github.com types. Refactor manager/manager/types to common/types and reuse them rather than redefine them.

Fixing some comments, etc.

Rather than hard-coding what a primitive is, we will only look for
templates, and let resourcifier error when kubectl fails to understand
anything else.

Adding missed new file.

When you deploy with <type>:<version>, the type actually seen by DM is
the template URL. While the template URL still shows up as the type when
performing a "dm deployed-types", this at least lets you look for
instances of a known type.

Refactoring the type URL code in client a bit.

Refactoring getTypeUrl.

The default is still either template file name or <type>-<version>.
Override using the "name" flag.

This endpoint takes a template and returns a manifest containing only
the expanded config and layout.

1) by type name: dm describe redis:v1
2) by URL: dm describe https://raw.githubusercontent.com/kubernetes/deployment-manager/master/templates/redis/v1/redis.jinja

Describing a type returns the template schema, which includes
descriptive information as well as the schema for properties on the
type.