Releasing v0.22.4.

Releasing v0.22.3.

Releasing v0.22.2.

Merge pull request square#845 from square/zachklipp/changelog-v0.22.1

Bump version number to v0.22.1 and update changelog.

Releasing v0.22.0.

Merge pull request square#763 from square/zachklipp/changelog-0.21.3

Update version numbers and changelog for v0.21.3

Merge pull request square#735 from square/zachklipp/changelog-version…

…s-v0.21.2

Update version numbers and changelog for 0.21.2.

Releasing v0.21.1.

Merge pull request square#701 from square/zachklipp/changelog-0.21.0

Update changelog and version for v0.21.0 release.

Merge pull request square#554 from square/zachklipp/prep-v0.20.0

Releasing v0.20.0.