Prepare to release v1.7.0 (uber-go#502)

Update the changelog for the 1.7.0 release.

Update changelog for 1.6.0 release (uber-go#498)

Cutting a release so we can reduce the noise in stacktraces.

Update changelog for 1.5.0 release (uber-go#481)

Two features and a bugfix are enough to warrant a minor release.

Add changelog entry for v1.4.1 (uber-go#442)

* Add changelog entry for v1.4.1

* Update to include more patches

Add changelog entry for v1.4.0 (uber-go#429)

Add a changelog entry for the 1.4.0 minor release.

Add v1.3.0 to changelog (uber-go#417)

* Add v1.3.0 to changelog

* Reword slightly

Add v1.2.0 to changelog (uber-go#407)

Add v1.1.0 to changelog (uber-go#398)

Really fix README link