Feature/fix ubuntu1404

Hi bedrock/roots peeps,

I had some issues installing this from scratch tonight, the following pull requests fixes all the issues I had:

- Tasks in main.yml needed to be run before other tasks
- Permissions issues on Ubuntu 14.04 / Vagrant NFS without no_root option
- Make sure www-data belongs to default user (vagrant)

Tonight was my first experience with Ansible so there's probably better ways of achieving what I have.

Submitting this as a pull request for visibility, and hopefully to help others rather than expecting it to be merged as is.

I hope this is okay! :)

Cheers

Alan