Refactored the API to more easily accept new endpoints. Added REST,
client, and CLI endpoints for getting logs from a specific task. All
that is needed after this commit to enable arbitrary service log
selectors is a REST endpoint and handler.
Task logs can be retrieved by putting in a task ID at the CLI instead of
a service ID.
Signed-off-by: Drew Erny <drew.erny@docker.com>
Upstream-commit: d330dc3223df7e6c2b066373718709e34e19efca
Component: engine
