Update CHANGES.txt before connectors release.
Update CHANGES.txt before connectors release.

	Change on 2018/02/22 by idv <idv@google.com>

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=186676192

GoogleCloudDataproc/hadoop-connectors,GoogleCloudDataproc/hadoop-connectors