KAFKA-5076: remove usage of java.xml.bind.* classes

[xvrl]

• replaces base64 from DatatypeConverter with Base64 introduced in JDK 8
• this change enables running Kafka with Java 9

Given that we plan to stop supporting Java 7 in 0.11 this should be fine, but merging this would depend on when we are comfortable introducing backwards-incompatible changes.

[asfbot]

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Test FAILed (JDK 7 and Scala 2.10).

[asfbot]

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Test PASSed (JDK 8 and Scala 2.11).

[asfbot]

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[ijuma]

We decided not to move to Java 8 for 0.11 in the end. So we may need another solution.

[asfgit]

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[ijuma]

@xvrl #3647 includes a solution that works in Java 7 and Java 9.

[asfgit]

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Test FAILed (JDK 7 and Scala 2.11).

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Test PASSed (JDK 8 and Scala 2.12).

[xvrl]

sounds good