using a shared folder can cause race conditions for the download
role as it tries to download files on all the nodes to the same
shared path.  This adds a flag to run the tasks in the download
role on just one node.

check_certs task "Check_certs | Set 'sync_certs' to true" was failing
due to the dict not existing, this sets defaults that allows the
correct behavior of the conditionals.

* set flannel backend type to `host-gw`
* set flannel interface to be eth1 ip

This allows you to simply run `vagrant up` to get a 3 node HA cluster.

* Creates a dynamic inventory and uses the inventory/group_vars/all.yml
* commented lines in inventory.example so that ansible doesn't try to use it.
* added requirements.txt to give easy way to install ansible/ipaddr
* added gitignore files to stop attempts to save unwated files
* changed `Check if kube-system exists` to `failed_when: false` instead of
`ignore_errors`

This shouldn't use the `inventory_hostname` variable, as that will just yield the same variable, but rather use the `host` which we're looping over.

This fixes the ansible error ```'dict object' has no attribute
'ansible_default_ipv4'"}```. Closes #215

cosmetic

as per @smana request

add option for generic

change hyperkube image repository

On CoreOS where there is no package management, perform zero-trip
loops instead of throwing an exception for iterating over a member
of an undefined variable.

On CoreOS the binaries are not installed in /usr/local/bin.

Changed path to hosts ssl certs from /usr/share/ca-certificates to /etc/ssl/certs/ which fixes https problems in kube-controller-manager and kube-apiserver (#189) caused by the lack of certificates on debian and redhat based systems.

When kubespray is deployed on OpenStack, the kube-controller-manager is now aware of the cluster and can create new cinder volumes automatically if the PersistentVolumeClaims are annotated accordingly.
Note that this is an alpha feature of kubernetes 1.2

Reverted deletion of "changed_when: False" for Task "Install python-dnf for latest RedHat versions". Deleted "changed_when: False" on Task "Install latest version of python-apt for Debian distribs" to get notified when kubespray has installed a new package version.