Move setup-network-environment.service to ansible

The below is current deployed by cloud config. Seems best to keep cloud config fairly light-touch and move this to ansible if we can to live in a 'common' role or somewhere near network related code (when we also move flannel).

```
name: setup-network-environment.service
command: start
content: |
[Unit]
Description=Setup Network Environment
Documentation=https://github.com/kelseyhightower/setup-network-environment
Requires=network-online.target
After=network-online.target

[Service]
ExecStartPre=-/usr/bin/mkdir -p /opt/bin
ExecStartPre=/usr/bin/curl -L -o /opt/bin/setup-network-environment -z /opt/bin/setup-network-environment https://github.com/kelseyhightower/setup-network-environment/releases/download/v1.0.0/setup-network-environment
ExecStartPre=/usr/bin/chmod +x /opt/bin/setup-network-environment
ExecStart=/opt/bin/setup-network-environment
RemainAfterExit=yes
Type=oneshot
```