Previously this was not checked so an existing record (e.g. with type A) would be overwritten on upsert by a record with the same name but different type (e.g. TXT).
This commit also:
* publicizes the type variable appending the underscore affix (required to maintain compatibility with CloudFormation which sets type as the CF type),
* fixes a wrong assumption in tests that UPSERT applies a change to Type (it creates a distinct record instead),
* Updates ACM model to use serial_number instead of deprecated and remove serial causing Travis failures.
d61ce0584b