Build JSON API changes

pulp_sync: no longer accepts username and password parameters
pulp_sync: now accepts optional registry_secret_path, insecure_registry, and pulp_repo_prefix parameters, allowing sync from V2 registry that requires authentication -- note: this requires dockpulp > 1.22
tag_and_push: registries can now include a "secret" key in their description, which is the path to the Kubernetes dockercfg secret required for pushing to the registry
bump_release: no longer accepts git_ref, author_name, author_email, committer_name, committer_email, commit_message, or push_url
bump_release: now requires parameters target (Koji build target) and hub (Koji hub URL)
tag_from_config: new available plugin

Bug fixes

plugins whose constructors fail are now handled correctly
intermediate docker registry links are not set in annotations if pulp_sync plugin is enabled
bump_release plugin now takes component version into consideration
tag_from_config plugin no longer accepts additional tags containing hyphens

pulp_sync is now able to ask Pulp to sync from a V2 registry that requires authentication
bump_release now uses a Koji hub to discover the latest release of the component and uses that to provide a value for the Release label if missing
new tag_from_config plugin to add additional tags to the image
API documentation was updated
Custom repo urls are supported for base images
koji_promote plugin now includes 'tags' field in build output metadata

New upstream release.

Exit plugins can now fail the build. All exit plugins are run at the end of the build regardless of whether the build has failed. Exit plugin failures for plugins marked as required for a successful build would previously not cause the build to fail, but they now do.
koji_promote: now accepts optional target parameter
pull_base_image: this plugin is no longer added if missing
tag_and_push: this plugin is no longer added if missing

docker build: fix logging so that it is properly decoded from JSON
koji_promote: use component, not name, to determine the name-version-release for the Koji build.