It would be very great to have the possibility to attach at least one file to at least Email and Slack notifications.
For failing builds it could sometimes a bit pitiful to find out what went wrong. In some cases, like instrumentation tests there is a report-html sitting there which I would really like to attach to an email or slack notification
I know this can be implemented by uploading something to S3 etc. but it would be more helpful to have this as a ready to use feature in Travis