Similar to Active Record - it will raise ActiveResouce::ResourceInvalid if
the resource is not valid (ie if <tt>valid?</tt> returns false)
However - does not raise ActiveResource::ResourceNotFound if the callbacks
fail (callbacks have not yet been implemented) - it will just try to save
and raise if the callbacks all fail.
This is not ideal behaviour - but will do until we decide to change the
behaviour of save_with_validations to actually raise (rather than catch) the
ResourceInvalid exception.
Signed-off-by: Joshua Peek <josh@joshpeek.com>
