Update owl-diff dependency for stable ordering and to avoid large string creation

[balhoff]

Resolves #1192. owl-diff now accepts a Writer or OutputStream so it can avoid creating a huge string. Also, the ordering of output should be consistent.

• docs/ have been added/updated
• tests have been added/updated
• mvn verify says all tests pass
• mvn site says all JavaDocs correct
• CHANGELOG.md has been updated

[balhoff]

I need to check the mvn verify results, since something is causing an error at the moment.

Fixed by removing unnecessary flush() call.

[jamesaoverton]

This seems straightforward to me, and it passes the tests. Ready for me to merge it @balhoff?

[balhoff]

Thanks @jamesaoverton, I think it's ready.