pkg_upstream_url is required in core plans
pkg_upstream_url is required in core plans

When using `hab plan init` to create a new core plan, we will fail the
build in travis because we're enforcing that all packages have a
project home page - `pkg_upstream_url`:

https://github.com/habitat-sh/core-plans/blob/master/bin/check-default-variables.sh

Signed-off-by: Joshua Timberman <d6955d9721560531274cb8f50ff595a9bd39d66f@chef.io>

rsertelon/habitat,nathenharvey/habitat,nathenharvey/habitat,rsertelon/habitat,nathenharvey/habitat,georgemarshall/habitat,habitat-sh/habitat,nathenharvey/habitat,habitat-sh/habitat,habitat-sh/habitat,georgemarshall/habitat,georgemarshall/habitat,habitat-sh/habitat,nathenharvey/habitat,rsertelon/habitat,rsertelon/habitat,habitat-sh/habitat,georgemarshall/habitat,habitat-sh/habitat,habitat-sh/habitat,georgemarshall/habitat,nathenharvey/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat,georgemarshall/habitat,georgemarshall/habitat,georgemarshall/habitat