Replace printHexBinary and add JDK 11 to travis

[tirkarthi]

• This removes dependency on DataTypeConverter which results in compile time error on JDK 11.
• Add JDK 11 to Travis

Closes #698

Ref implementation : https://github.com/twosigma/webtau/pull/58/files

[alandipert]

This is great, thank you. Could you please add a note to CHANGELOG.md describing the change?

[tirkarthi]

I have added a changelog entry but it might have some merge conflicts when other PRs are merged and I will resolve it.

Thanks