Support multiple "clouds"

[jschementi]

Currently only AWS is supported, but it'd be interesting to also support other clouds, like Digital Ocean, Rackspace, etc.

[jschementi]

This will require quite a bit of refactoring up-front, as AWS support needs to be an adapter. Then, support for other clouds would be straight-forward, as long as they have the same features as AWS. However, if one feature is missing, like a load balancer, the adapter would have to provision a load-balancer manually (using nginx or haproxy, for example).