Merge branch 'issue_14189' into 'master'

CHANGELOG

app/assets/javascripts/LabelManager.js.coffee

app/assets/javascripts/dispatcher.js.coffee

app/assets/stylesheets/framework/lists.scss

app/assets/stylesheets/pages/labels.scss

app/controllers/projects/labels_controller.rb

app/finders/issuable_finder.rb

app/helpers/sorting_helper.rb

app/models/concerns/issuable.rb

app/models/issue.rb

app/models/label.rb

app/views/projects/labels/_label.html.haml

app/views/projects/labels/index.html.haml

app/views/shared/_issues.html.haml

app/views/shared/_label_row.html.haml

app/views/shared/_sort_dropdown.html.haml

config/routes.rb

db/migrate/20160314094147_add_priority_to_label.rb

db/schema.rb

features/steps/project/issues/labels.rb