add specs for correct linkversion on link.
add a link_version_id field to links.
add current_version for links and version-setting.
upgrade sidekiq to 3.1 and sidekiq dependents

Additionally upgrade sidetiq and sidekiq-failures.
upgrade every bundled gem in bounds.
add new bounds for rails_config

Versions greater than 0.3 (0.4 series and up) won't
work for us, as they require to be loaded inside
a rails environment.
Merge pull request #932 from ontohub/perform_necessary_upgrades

Perform necessary upgrades
Merge pull request #931 from ontohub/924-enable_current_version_support_for_links

924 enable current version support for links
Revert "fast fix for show page of links"

This reverts commit ce83c09ae0206e478602ce4152cfa788dd366f59.
Merge branch 'staging' into 620-ontologies_in_mappings_should_be_clickable