Fix #61 - Add list of blocked users to the UI; clean up failed push notifications API

.travis.yml

Gemfile

Gemfile.lock

app/assets/javascripts/components/actions/blocks.jsx

app/assets/javascripts/components/containers/mastodon.jsx

app/assets/javascripts/components/features/blocks/index.jsx

app/assets/javascripts/components/reducers/accounts.jsx

app/assets/javascripts/components/reducers/user_lists.jsx

app/models/device.rb

app/services/notify_service.rb

app/services/send_push_notification_service.rb

db/migrate/20170205175257_remove_devices.rb

db/schema.rb

spec/fabricators/device_fabricator.rb

spec/lib/formatter_spec.rb

spec/models/device_spec.rb