Update ssh key names and Hobbes image id.
Add some more information on MacOSX installation
Add more information on how to deploy the default configuration file
and to edit it.
Comment all the options that need to be replaced with real values,
including:

* `image_user` (in `login/google` section)
* `ec2_access_key`, `ec2_secret_key` in `cloud/ec2hobbes` and
  `cloud/amazon-us-east-1` sections
* `username`, `password` and `project_name` in `cloud/hobbes` section
* `gce_client_id`, `gce_client_secret` and `gce_project_id` in
  `cloud/google` section
Specify that when run with `-vvvv` elasticluster will *not* fork.
Squashed 'elasticluster/providers/ansible-playbooks/' changes from a5ab13f..c1dd701

c1dd701 Fix issue with munge and `/var/log` permissions on Ubuntu 14.04
a98ca17 Fix nfs-client.yml task for Ubuntu 14.04: `portmap` service has been replaced by `rpcbind`

git-subtree-dir: elasticluster/providers/ansible-playbooks
git-subtree-split: c1dd701aaba95a613c7a83b66bd0e779886a948e
Merge conflicts in playbooks
Squashed 'elasticluster/providers/ansible-playbooks/' changes from c1dd701..b4cec78

b4cec78 Do not use '{{' when it's not needed
1f10f2b Include fix from kern3020 (https://github.com/kern3020) for issue #117: "why is an Ubuntu task run on a debian system?"
69c5c7e Simplify `when:` conditional
5c454ca Do not look for `is_ubuntu_or_debian` when you are looking for a specific ubuntu version...
219103d Add support for *extending* a gluster filesystem
99a1a23 Fix typo
981ac47 Merge branch 'ansible-1.6'
3e6758b Fix more playbooks
25157e0 Fix core-site.xml file not correctly parsed by hadoop
f8ac36a Fix gluster playbooks
c868723 More bugfix
a59fe6f Fix playbooks for slurm/precise
e541004 Update playbooks to work with Ansible 1.7.2
51d1320 Merge pull request from John Morrissey (https://github.com/jwm)
fc2c1a7 Update to use current ansible version (1.7.2)

git-subtree-dir: elasticluster/providers/ansible-playbooks
git-subtree-split: b4cec78713c52d30bae57236c3005e37c0c54fda
Merge ansible playbooks
Update documentation: specify that in order to install on MacOSX you
need to have Xcode installed.
avoid pickle assertion failure on something in boto
add vpc support
set connection state ~atomically, preventing race condition in setup threads
gracefully handle subnets with no Name tag
have slurm schedule cores as consumable resources, not just memory