Added AWS cloud compatibility

Updated example config and schema to allow for the selection of a
single cloud provider (openstack or aws).
Updated svmp module to select appropriate cloud module.
Updated openstack module with appropriate error handling for config
and new user model.
Added aws module with identical functionality as openstack module,
except removed floating ip functionality.
Fixed users module, small compatibility issues that broke when new
user model was added.
Updated protocol module to hide passwords from 'silly' logging.
Updated cli module to clarify the difference between 'add' and
'add-user-with-volume' commands, also changed 'clear-vm-info'
command to only clear VM info, not volume info.
Merge pull request #5 from jportner/master

Added AWS cloud compatibility