Adding AWS support to openshift-ansible module

- Update documentation to say that ssh configuration need to point to the private key file
- Removing the -p argument when calling time .... because it is misintrepreted by ruby
- Turning the cluster.sh to agnostic in its help/error message by replacing explicit reference to GCE by a a variable
- Fixing a bug within the playbooks that incorrectly references the minions and master fact group. Needs a better fix with a call to AWSHelper.generate_env_host_type_tag_name()
- Adding playbooks for AWS, which are almost of copy/paste for those of GCE: Needs a refactor to reduce code duplication
This is only needed if they don't have their ssh key loaded in their ssh agent. I think an exception should be added saying "if you don't have your key loaded in your ssh agent, then add this to your config file.

Also, doing the config option isn't as nice as the ssh agent because here you're restricting all AWS host to a single key. What if they have multiple ssh keys that they use in AWS (like per host type or whatever). The agent will make it work for all, this config approach will restrict it to 1 key.