add color logging capabilities for promlog
Add's color logging capabilities to promlog when we're logging to the terminal, otherwise we just get a standard go-kit logger when logging to a file. We'll have to update deps/vendor packages in prometheus after we merge.
cc: @krasi-georgiev @juliusv
cc: @fabxc
Did you check if colours can be applied to selected name=value groups rather than the entire line?
AFAICT, that would require a change to the go-kit/log/term package. So unless anyone thinks it's really necessary, I'll just leave the colors change as is for now.
Is this still wanted?
This PR seems fine, but it needs a rebase for the change to go-kit/log