fix(plugin): monkey-patch coreos plugin

Override the behavior of the upstream coreos guest
plugin to make it work with usr images.
doc(README): drop alt-setup
feat(provision): Add coreos-cloudinit provisioner
Merge pull request #45 from bcwaldon/fix-usr

Override upstream plugin; Add cloudinit provisioner
doc(README): Adjust to new command syntax for vagrant box remove
Merge pull request #48 from gmacario/fix-boxremove

doc(README): Adjust to new command syntax for vagrant box remove
fix(clustering): Use same codepath for single- and multi-node
Merge pull request #47 from bcwaldon/fix-usr

Implement clustering with coreos-cloudinit
fix(Vagrantfile): use amd64-usr for vmware
Merge pull request #54 from philips/usr-image-vmware

fix(Vagrantfile): use amd64-usr for vmware
refactor(plugin): Use cloud-config to provision networks and hostname
Merge pull request #51 from bcwaldon/refactor-plugin

refactor(plugin): Use cloud-config to provision networks and hostname
fix(plugin): temporary fix for missing /etc/environment
Merge pull request #58 from bcwaldon/fix-env

Temporary fix for missing /etc/environment
fix(user-data): make discovery more clear
Merge pull request #59 from robszumski/master

fix(user-data): make discovery more clear
fix(plugin): Remove /etc/environment hack
fix(ip): use private address space

Replace usage of 172.12.8.0/24 with 172.17.8.0/24
Merge pull request #62 from bcwaldon/private-address-space

fix(ip): use private address space
Get NUM_INSTANCES from env var

So the git repo doesn't get dirty...