validate: empty user_data is also valid
Merge pull request #283 from crawford/validate

validate: empty user_data is also valid
network: write network units with user units

This allows us to test the network unit generation as well as removing
some special-cased code.
Merge pull request #282 from crawford/network

network: write network units with user units
test: disable Travis sudo capability
Merge pull request #284 from crawford/travis

test: disable Travis sudo capability
coreos-cloudinit: bump to v1.0.2
coreos-cloudinit: bump to v1.0.2+git
Godeps: switch to coreos/yaml
Merge pull request #286 from jonboulle/master

Godeps: switch to coreos/yaml
Create an environment file for flannel

Rather than using a systemd overlay, allow docker to load the
environment file. This is due to coreos/coreos-overlay#1002