Shorten metadata timeout
Shorten metadata timeout

When running in travis, metadata requests will timeout after 5 seconds.
After 24 such timeouts, we'll hit travis' build timeout of two minutes,
and the build will fail. Lowering it to 100 gets us in a safe time
limit. We _may_ need to expose a timeout env var with this logic,
however.

dave2/packer,dave2/packer,timsutton/packer,ChrisLundquist/packer,ChrisLundquist/packer,paulmey/packer,p1-nico/packer,p1-nico/packer,tb3088/packer,arizvisa/packer,p1-nico/packer,youhong316/packer,youhong316/packer,mkuzmin/packer,ricardclau/packer,pecigonzalo/packer,jen20/packer,grubernaut/packer,routelastresort/packer,tb3088/packer,bryson/packer,p1-nico/packer,grubernaut/packer,paulmey/packer,tb3088/packer,tb3088/packer,bryson/packer,youhong316/packer,rnaveiras/packer,ricardclau/packer,bryson/packer,mkuzmin/packer,youhong316/packer,ChrisLundquist/packer,jen20/packer,ricardclau/packer,pieter-lazzaro/packer,mkuzmin/packer,pieter-lazzaro/packer,markpeek/packer,mitchellh/packer,markpeek/packer,rnaveiras/packer,arizvisa/packer,pieter-lazzaro/packer,pieter-lazzaro/packer,arizvisa/packer,routelastresort/packer,rnaveiras/packer,routelastresort/packer,mkuzmin/packer,taliesins/packer,taliesins/packer,bryson/packer,timsutton/packer,grubernaut/packer,taliesins/packer,markpeek/packer,ricardclau/packer,arizvisa/packer,KohlsTechnology/packer,pecigonzalo/packer,tas50/packer,mitchellh/packer,paulmey/packer,mitchellh/packer,ricardclau/packer,mkuzmin/packer,jen20/packer,tas50/packer,tb3088/packer,paulmey/packer,hashicorp/packer,mkuzmin/packer,markpeek/packer,tas50/packer,timsutton/packer,rnaveiras/packer,youhong316/packer,taliesins/packer,paulmey/packer,dave2/packer,pieter-lazzaro/packer,timsutton/packer,p1-nico/packer,hashicorp/packer,ChrisLundquist/packer,p1-nico/packer,tas50/packer,dave2/packer,ricardclau/packer,KohlsTechnology/packer,bryson/packer,ChrisLundquist/packer,taliesins/packer,pecigonzalo/packer,hashicorp/packer,KohlsTechnology/packer,dave2/packer,youhong316/packer,ChrisLundquist/packer,mitchellh/packer,KohlsTechnology/packer,tas50/packer,timsutton/packer,tb3088/packer,mitchellh/packer,taliesins/packer,jen20/packer,grubernaut/packer,KohlsTechnology/packer,tas50/packer,paulmey/packer,routelastresort/packer,jen20/packer,pecigonzalo/packer,rnaveiras/packer,arizvisa/packer,arizvisa/packer,jen20/packer,grubernaut/packer,routelastresort/packer,hashicorp/packer,bryson/packer,rnaveiras/packer,markpeek/packer,dave2/packer,timsutton/packer,markpeek/packer,KohlsTechnology/packer,pieter-lazzaro/packer,grubernaut/packer