add spec for a timeout worker.
add default timeout limit (6 hours).
add TimeoutWorker

Tests should be green.
Also StateUpdater methods are not protected anymore (we should be able
to manipulate the state from outside of the model).
add convenience methods for timeout-clock.
add specs for worker if timeout not reached.
adjust timeout worker for rescheduling

Utilize Sidekiqs scheduling capability.
Also allow rescheduling if timeout was not
yet reached.
use timeout-worker in worker and batch-parse.
rely on sidekiqs scheduling mechanism

Instead of second-guessing sidekiq by checking the timeout again (and
considering that sidekiq basically checks it the same way we were doing
it), we rely on sidekiqs scheduling mechanism.
rename state updater and remove duplicate.
allow versions controller to render json-show.
add status_tag helper and use in in info/versions

status_tag wrap the status-helpermethod. It provides
the information which is necessary for the automatic
polling status updater.
adjust automatic state poller

state poller should now be functional again.
prevent poll-implosions for automatic state-update

Instead of calling enqueue inside of the loop (so for every turn every
element gets a new enqueue for all elements, we enqueue updates
element-wise.

Later on we could even further optimize that by using
ontology_version_id to only poll for each version once per 'tick'.
refactor links controller collection.
sort links#index by source.logic

Sort the links in an index view by the logic of the source-ontology of
the link.

Also extract the search-triple ontology_id, source_id, target_id into
its own method.
optimize links controller further

Apply special order to links collection in every
case.
Also set @links instance variable in every case.
And cut down on the obsolete/duplication.
add invoker to Gemfile.
add invoker configuration file.
Merge branch 'staging' into 482-sort_mappings_by_source_logic

Conflicts:
	app/models/link.rb
Merge pull request #934 from ontohub/482-sort_mappings_by_source_logic

482 sort mappings by source logic