Release 0.20.0

Major Features

• S3 and HDFS file system supports fully migrated from tensorflow to tensorflow-io package.
• Add tutorial of MongoDB support with tensorflow-io.
• Add tutorial of ORC support with tensorflow-io
• Add batched string support for Apache Arrow.

Bug Fixes

• Fix decode_video returning only the first frame.
• Reset mongo cursor after reaching end of collection.

Thanks to our Contributors

This release contains contributions from many people:

Aleksey Vlasenko, Gerard Casas Saez, Keqiu Hu, Kota Yamaguchi,
Mark Daoust, Vignesh Kothapalli, Yong Tang, austinzh

We are also grateful to all who filed issues or helped resolve them, asked and
answered questions, and were part of inspiring discussions.