Add integration to upload results to some "pastebin"

[yarikoptic]

We should not implement those integrations but use some external library/toolkit for that. But it should be optional (configurable). I personally would prefer helper which could be configured to use https://paste.debian.net/ .

• Might also need to be configured to upload only last N lines etc.
• May be there is a service which could get .md and with figures so we could even configure to upload rendering of _stats.json progression
• _info.json better be uploaded pretty-printed