Updates to pgweb .mailmap

I noticed that we had more entries in the commitlog that need normalization
(name and/or spelling on Joe and Álvaro). I'll apply the below diff unless
there are objections:

diff --git a/.mailmap b/.mailmap
index a248e105..5a05cef8 100644
--- a/.mailmap
+++ b/.mailmap
@@ -3,3 +3,5 @@ Devrim Gündüz <devrim(at)gunduz(dot)org> Devrim Gunduz <devrim(at)gunduz(dot)org>
Sarah Conway <sarah(dot)conway(at)crunchydata(dot)com> xenophenes <sarah(dot)conway(at)crunchydata(dot)com>
David Rader <davidr(at)openscg(dot)com> Rader, David <davidr(at)openscg(dot)com>
Jonathan S. Katz <jonathan(dot)katz(at)excoventures(dot)com> Jonathan Katz <jonathan(dot)katz(at)excoventures(dot)com>
+Joe Conway <mail(at)joeconway(dot)com> jconway2 <jconway2(at)nautilus(dot)joeconway(dot)com>
+Álvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>

--
Daniel Gustafsson