Update version to 2.1.0-cdo.3

[fisher-alice]

This PR updates the version of @code-dot-org/johnny-five to 2.1.0-cdo.3.
I attempted to publish version 2.1.0-cdo.2 to the NPM registry after merging this PR which included an update to the Rgb class method pulse and additional unit tests.
However, I received the following error when I ran npm version 2.1.0-cdo.2:

This was puzzling since the last version published was 2.1.0-cdo.1 shown when I ran npm view @code-dot-org/johnny-five versions. (Ignore the 2.1.0-cdo.3 since published!):

But @bencodeorg pointed me to this post. After running npm view @code-dot-org/johnny-five time, I remembered that I published by mistake, then unpublished version 2.1.0-cdo.2 a couple months ago:

Once you publish/unpublish a version, it is unique and cannot be reused. See https://docs.npmjs.com/unpublishing-packages-from-the-registry.

Thus, the newest version of @code-dot-org/johnny-five is now at 2.1.0-cdo.3.