Respect additional authorization token field

[sjahreis]

Docker specifies the following token headers during registry authorization:

• token: An opaque Bearer token that clients should supply to subsequent requests in the Authorization header.
• access_token: For compatibility with OAuth 2.0, we will also accept token under the name access_token. At least one of these fields must be specified, but both may also appear (for compatibility with older clients). When both are specified, they should be equivalent; if they differ the client's choice is undefined.

See https://github.com/docker/distribution/blob/master/docs/spec/auth/token.md#token-response-fields for more details.

The bundle-lib only accepts the access_token field. See https://github.com/automationbroker/bundle-lib/blob/master/registries/adapters/oauth/client.go#L35-L37 and https://github.com/automationbroker/bundle-lib/blob/master/registries/adapters/oauth/client.go#L191 for more details.

But registries like Artifactory or Harbor send their token in the field token. Therewith we couldn't connect them with the Automation Broker.

I'll create a PR which respects the additional token field token as well.

[eriknelson]

@sjahreis Once this PR merges (openshift/ansible-service-broker#1167), CI should build and publish you a new image at docker.io/ansibleplaybookbundle/origin-ansible-service-broker:canary, you can check the status of that here https://hub.docker.com/r/ansibleplaybookbundle/origin-ansible-service-broker/tags.

[sjahreis]

@eriknelson: Thanks! :-)