Adjust part size as needed in create_archive_from_file

Fixes #1478, original patch suggested by @dminkovsky.
If we have a large enough file such that the default part size
is not sufficient to stay within the maximum number of parts
allowed by glacier, we automatically adjust the part size
to the minimum required.  We were previously calculating this
value but not actually doing anything with it.
Add release note item for bug fix
Merge branch 'glacier-partsize-fix' into develop

Closes #1478

* glacier-partsize-fix:
  Add release note item for bug fix
  Adjust part size as needed in create_archive_from_file