Add release notes for 1.3.0 and 1.4.0.0a1/2

We appear to have stopped doing these since the 1.2.0 release, but I
like to do them because it helps highlight new APIs, behavior changes,
important bug fixes, new dependencies and also allows us to credit the
contibutors in a nice and friendly way.

Change-Id: I7dd6641a840dee0082c6c9e9216184f385869519