LXC managment improvments

- Add functions to the module
- Introduce a new state module to manage lxc containers via salt states
salt.cloud: pep8
salt.cloud: Better multiprocessing handling
salt.cloud: race because of wrong configuration
salt.states.cloud: py3k dict iter
salt.modules.cloud: virtual return name
salt.states.cloud.present: fix mis-use of provider

provider as a special meaning in salt ...
http://docs.saltstack.com/ref/states/providers.html
salt.cloud: race: if misconfiguration, boolean instead of dict
salt.modules.lxc: add ip & size to infos
salt.cloud.lxc: lxc provider