* Added checks to make ci for yaml linting
* Modified y(a)ml files to pass lint checks

Attempting to create a GCE cluster when the `gce.ini` configuration file
contains a non-default network leads to the following error:
```
TASK [Launch instance(s)] ******************************************************
fatal: [localhost]: FAILED! => {"changed": false, "failed": true, "msg": "Unexpected error attempting to create instance lenaic2-master-74f10, error: {'domain': 'global', 'message': \"Invalid value for field 'resource.networkInterfaces[0]': ''. Subnetwork should be specified for custom subnetmode network\", 'reason': 'invalid'}"}
```

The `subnetwork` parameter needs to be added and taken into account.

The Ansible GCE module (documentation here: http://docs.ansible.com/ansible/gce_module.html) requires a comma separated list when you pass an array here (even with a single element) the argument has square brackets around it and the instance doesn't get launched.  Testing shows that joining with ', ' (comma space) works with one instance but breaks with two so I used ',' (comma no space).