standalone validation tool fails for @@DOMAIN_HOME@@ tokens

[ddsharpe]

When the domain model contains a @@DOMAIN_HOME@@ token for an attribute value, the stand-alone validation tool will fail validation with a python exception. Since stand-alone validation does not have a domain home value, resolution results in a null value being passed to the string conversion.

For internal @@ tokens like DOMAIN_HOME that will be resolvable at run-time during create operations, validation should not fail these attributes in stand-alone mode.