go-bindata dependency doesn't install by default

[willscott]

on a mac, running 'make' didn't trigger the go-bindata dependency until i explicitly ran make bindata.

The initial query for version doesn't seem to work as expected when the dependency is uninstalled, instead resulting in the following terminal output:
/bin/sh: go-bindata: command not found
this is at https://github.com/OpenObservatory/gooni/blob/master/Makefile#L1

Is there a reason go-bindata isn't vendored? if installed as a vendor dependency it should then be runnable as go run vendor/github.com/shuLhan/go-bindata/go-bindata/main.go