Merge pull request #965 from noesya/posts_pinned

...rollers/admin/communication/extranets/posts_controller.rb

app/models/communication/extranet.rb

app/models/communication/extranet/post.rb

app/views/admin/communication/extranets/posts/_form.html.erb

app/views/admin/communication/extranets/posts/show.html.erb

config/locales/communication/en.yml

config/locales/communication/fr.yml

...30317160229_add_pinned_to_communication_extranet_posts.rb

db/schema.rb

test/fixtures/communication/extranet/posts.yml

test/fixtures/communication/extranets.yml

test/models/communication/extranet/post_test.rb

test/models/communication/extranet_test.rb