abstract model - setting resources made consistent

...with setting resource_name
comp. res. cli - actions list and info
comp. res. - api, model for each provider
comp. res. cli - create
cli - case insensitive choices for optparse options
comp. res. cli - case insensitive provider choices
comp. res. cli - updating
comp. res. api - support for updates

Validation of provider-specific attributes is temporarily disabled
until Foreman implements returning all attributes
on compute_resource_controller#show.
simple crud controller - support for custom as_json options
comp. res. api - fixed json root
comp. res. cli - deleting
comp. res. cli - fix in params for rackspace
comp. res. - system tests
comp. res. cli - provider specific fields in info
comp. res. api - finding correct model class