Add S3 storage type to avatars

...s/rocketchat-file-upload/client/lib/FileUploadAmazonS3.js

...es/rocketchat-file-upload/client/lib/fileUploadHandler.js

packages/rocketchat-file-upload/globalFileRestrictions.js

...hat-file-upload/server/config/configFileUploadAmazonS3.js

packages/rocketchat-file-upload/server/lib/FileUpload.js

packages/rocketchat-lib/server/models/Uploads.coffee

packages/rocketchat-ui-account/client/avatar/prompt.coffee

packages/rocketchat-ui/client/lib/fileUpload.js

packages/rocketchat-ui/package.js

server/methods/setAvatarFromService.js

server/startup/avatar.js