Add ephemeral play support for Colab. (#980)
Add ephemeral play support for Colab. (#980)

* Add ephemeral playback to notebook_utils for colab

* lint

* lint

* lint

* lint

* Add python3 support for stringio

* Import cStringIO only in Colab since it is not Python3 compatible

* Switch to BytesIO for py2/3 compatibility.

magenta/note-seq,magenta/note-seq,magenta/note-seq