Revert "Add sandbox API for task insertion to service LB and service discovery"

[sanimej]

This reverts commit 2fb2fd2.

This change was to support container health aware LB and graceful rolling upgrade. Without the docker and swarmkit changes for these features libnetwork can't be vendored in. Hence reverting it now and will be included when the docker/swarmkit changes are complete. cc @dongluochen

[GordonTheTurtle]

Please sign your commits following these rules:
https://github.com/docker/docker/blob/master/CONTRIBUTING.md#sign-your-work
The easiest way to do this is to amend the last commit:

$ git clone -b "revertlb" git@github.com:sanimej/libnetwork.git somewhere
$ cd somewhere
$ git commit --amend -s --no-edit
$ git push -f

Ammending updates the existing PR. You DO NOT need to open a new one.

[aboch]

LGTM

[mrjana]

LGTM

[liweinan0423]

@sanimej Could you give more details why this commit is reverted? What changes in docker and swarmkit have to be done before we could get this commit back?

[sanimej]

@liweinan0423 This change introduces libnetwork APIs to enable/disable the service associated with the task. The changes needed (being worked on) on the docker side is to invoke the new APIs during task creation & deletion.