GLOBAL: Introduce project configuration files

In order to have a solid ground for further testing & development we introduce some
files that configure the environment for this project:

- `ansible.cfg`

We use this file to set global settings for ansible.

See http://docs.ansible.com/intro_configuration.html#the-ansible-configuration-file

- `.gitignore`
  Ignore some files from version control

- `Gemfile`
  This file documents the [Rubygems](http://rubygems.org/) we use

- `host.ini`
  Add todos to clarify usage if IPs

- travis-ci: Introduce `.travis.yml`
  This file configures our build environment on travis-ci:

    https://travis-ci.org/typo3-ci/infrastructure

- `Vagrantfile`
  In order to test our `ansible` setup locally we use Vagrant.
  See http://docs.vagrantup.com/v2/provisioning/ansible.html for details.
  We use `vagrant-cachier` plugin to cache external packages like `apt`, `gem` etc.

Run `rake install` to install all required plugins
Rakefile: Introduce tasks for common actions

In order to execute commands through a common interface, we introduce
`rake` and tasks to create & test roles.

Run this command to get a list of all tasks:

    rake -T
features: Add a high level feature description
spec: Initial version for `serverspec` tests

These tests are written in http://serverspec.org/.

In order to run them you need ruby and all required gems.

See [README.md](README.md) for details.
roles: Initial version of basic roles

See http://docs.ansible.com/playbooks_roles.html for more details on
roles.

We add infos from old chef cookbooks for further reference

These can be converted to Ansible tasks or can be deleted over time.
role:tertaker: Add legacy scripts from old gem

These scripts should be refactored into Jenkins' Job DSL and a Groovy
script to avoid the dependency on this Rubygem (and Ruby).

We can still use ruby for scripting but nowadays we can use more
elaborated techniqes as the Job DSL to create and manage the jobs.

Groovy can take care of the XML dance (which is currently done by
`nokogiri`).

Goal: Simplify the toolset and use tools that are already there (like
Groovy and Job DSL) instead of re-inventing the wheel.
playbook: Disable some roles for now

We will enable them when the roles are ready & tested.