JCLOUDS-619

Hello,

this is the fix for the issue described here[1].

Please review and let me know if you need something else.

Thanks and kind regards
Markus

[1] https://issues.apache.org/jira/browse/JCLOUDS-619
Do we need this complexity?  We can name parts with a fixed 8 character width base as in the Swift examples.  This should allow 10 million parts and even with the minimum 1 MB part size this allows 100 TB objects.  Trying to pick the minimum base also precludes streaming large objects where the caller does not know the final object size.