Update code owner for contrib/{kafka,kinesis}

Add myself so that issues or PRs could be assigned to me.

Note contrib/{kafka,kinesis} might be moved:
tensorflow/community#18

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

CODEOWNERS

@@ -61,5 +61,8 @@
 /tensorflow/contrib/tpu/ @frankchn @saeta @jhseu @sourabhbajaj
 /tensorflow/contrib/training/ @joel-shor @ebrevdo
 /tensorflow/contrib/util/ @sherrym
+/tensorflow/contrib/kafka @yongtang
+/tensorflow/contrib/kinesis @yongtang
+/tensorflow/contrib/hadoop @yongtang
 
 /third_party/systemlibs/ @perfinion