@param name<String> The name of the constant to get, e.g. "Merb::Router".
@return [Object] The constant corresponding to the name.
@param name<String> The name of the constant to get, e.g. "Merb::Router". @param value<Object> The value to assign to the constant.
Override this in a child if it cannot be dup‘ed
@return [Object]
[Validate]