HTTP connections must be explicitly closed in many cases, and letting
perform method close connections makes its callers less redundant and
prevent them from forgetting to close connections.

Currently, Mastodon will retry delivering toots for a bit over 1 hour.
This is a very short timespan when considering private and direct toots, which
cannot be seen by the recipient at all after the delivery attempts have failed.

Ideally, private and direct toots should have a different number of retries,
but I do not know how to do that.

* Close connection when succeeded posting

* Update webmock

- A successful delivery cancels it out
- An incoming delivery from account of the inbox cancels it out

* Deliver ActivityPub Like

* Deliver ActivityPub Undo-Like

* Deliver ActivityPub Create/Announce activities

* Deliver ActivityPub creates from mentions

* Deliver ActivityPub Block/Undo-Block

* Deliver ActivityPub Accept/Reject-Follow

* Deliver ActivityPub Undo-Follow

* Deliver ActivityPub Follow

* Deliver ActivityPub Delete activities

Incidentally fix #889

* Adjust BatchedRemoveStatusService for ActivityPub

* Add tests for ActivityPub workers

* Add tests for FollowService

* Add tests for FavouriteService, UnfollowService and PostStatusService

* Add tests for ReblogService, BlockService, UnblockService, ProcessMentionsService

* Add tests for AuthorizeFollowService, RejectFollowService, RemoveStatusService

* Add tests for BatchedRemoveStatusService

* Deliver updates to a local account to ActivityPub followers

* Minor adjustments