Merge branch 'optimistic-chat-posting' into 'develop'

src/components/chat/chat.js

src/components/chat/chat.vue

src/components/chat_message/chat_message.scss

src/components/chat_message/chat_message.vue

src/components/post_status_form/post_status_form.js

src/components/post_status_form/post_status_form.vue

src/modules/api.js

src/modules/chats.js

src/services/api/api.service.js

src/services/chat_service/chat_service.js

src/services/chat_utils/chat_utils.js

src/services/entity_normalizer/entity_normalizer.service.js

test/unit/specs/services/chat_service/chat_service.spec.js