Add cross suffix customizability for modules

For each module whose version can be specified using
the property "xxx.version.number", it is now possible
to specify its cross version suffix by using an
optional property "xxx.cross.suffix".

If such a property is not defined, then continue to
use the string "_${scala.binary.version}", as before.
fix to partest.cross
Merge pull request #3394 from cunei/wip-cross-suffix

Add cross suffix customizability for modules