go.talks/pkg/present: remove remaining log.Fatal calls
go.talks/pkg/present: remove remaining log.Fatal calls

R=bsiegert
CC=golang-dev
https://golang.org/cl/7311092

Karthikvb/talks,Karthikvb/talks,Karthikvb/talks,Karthikvb/talks,Karthikvb/talks,Karthikvb/talks