Interface::getVersionIntegers doesn't return the full version

Hi,

I noticed that in the latest MaterialX version, a new version of the standard surface was introduced. It's labeled as version "1.0.1" and the previous one is "1.0.0".
Unfortunately the `Interface::getVersionIntegers` helper only returns the first 2 numbers, which makes it a bit awkward to use :)
Not a very big issue, but it would be nice if that method would return the 3 numbers, like the `getVersionIntegers` found in the `MaterialXCore/Utils.h` header.

Regards,
Damien.

Locate Interface::getVersionIntegers and compare it with getVersionIntegers in the MaterialXCore/Utils.h header. Verify how the helper handles versions such as 1.0.0 and 1.0.1, then confirm that its result includes all three version numbers.

Written by the indexing model from the issue text.