Merge pull request #1658 from RocketChat/improvements/upload

packages/rocketchat-integrations/server/api/api.coffee

...tchat-message-attachments/client/messageAttachment.coffee

...ketchat-message-attachments/client/messageAttachment.html

packages/rocketchat-message-attachments/package.js

packages/rocketchat-ui-message/message/message.coffee

packages/rocketchat-ui-message/message/message.html

packages/rocketchat-ui/lib/fileUpload.coffee

packages/rocketchat-ui/views/app/room.coffee