Merge branch 'cleanup/unused-code' into 'master'

app/models/chat/chat_channel.rb

app/models/chat/chat_channels_user.rb

app/models/chat/chat_message.rb

app/models/group.rb

app/models/mailers/admin_mailer.rb

app/models/page/linking.rb

app/models/poll/request_vote.rb

app/models/private_post.rb

app/models/requests/request.rb

app/models/requests/request_to_destroy_our_group.rb

app/models/requests/request_to_remove_user.rb

app/models/requests/votable_request.rb

app/models/user.rb

app/models/user/chat_channels.rb

db/migrate/20171112160108_drop_messages.rb

db/migrate/20171112160203_drop_channels.rb

db/migrate/20171112160223_drop_channels_users.rb

db/schema.rb

lib/dummystrings.rb

lib/tasks/cleanup.rake