Rename "gopkg.in/fsnotify.v1" to "github.com/fsnotify/fsnotify"
per upstream recommendation.
See https://github.com/fsnotify/fsnotify/issues/108 for rationale.
Hugo has been confirmed which runs on Golang 1.6, as travis uses 1.6
vesion. Dockerfile must be consistend with it so it has to use golang:1.6
as base image than golang:1.5