Update changelog for 1.5.1, along with unreleased changes (#784)

Update CHANGELOG for the 1.5 release. (#654)

Update CHANGELOG for release 1.4.0 (#640)

Update CHANGELOG date (#625)

Update changelog with latest changes (#600)

Update changelog for 1.2.3 release (#580)

Update changelog for 1.2.2 release (#549)

Update changelog for 1.2.1 release (#540)

Update changelog for 1.2.0 release (#518)

Update changelog for 1.2.0 release and
update README code sample for latest version

Resolves #500.

Update changelog for 1.1.4 release (#478)