Defaul to the configured hostname in Run()
Defaul to the configured hostname in Run()

If Run() isn't passed a hostname to set, but we have one that was set
directly or inherited from the source image, use that value.

Signed-off-by: Nalin Dahyabhai <nalin@redhat.com>

Closes: #121
Approved by: rhatdan

rhatdan/buildah,nalind/buildah,nalind/buildah-1,TomSweeneyRedHat/buildah,projectatomic/buildah,TomSweeneyRedHat/buildah,nalind/buildah-1,rhatdan/buildah,rhatdan/buildah,TomSweeneyRedHat/buildah,nalind/buildah-1,projectatomic/buildah,ipbabble/buildah,nalind/buildah,projectatomic/buildah,ipbabble/buildah