feat(controller): allow tags for `deis pull`

if the source Build object specifies a tag to be pulled, it will use
that tag as the source rather than `latest`.
chore(registry): bump commit
Merge pull request #1496 from deis/1404-deis-pull-tag

feat(controller): allow tags for `deis pull`
fix(controller/registry): strip hostname from repo

The changes to the registry module did not strip the hostname from the
app image. This fixes that by properly parsing the source for the
repository name in the registry and the tag.
Merge pull request #1500 from deis/hotfix-registry-module

fix(controller/registry): strip hostname from repo
fix(tests): allow env vars to override important test settings
refactor(tests): update test expectations and get suite passing
docs(tests): update README.md with integration test setup