bindings: move go bindings to contrib

This signals two things, an intent to be more liberal about accepting
patches, and an intent to stop distributing the bindings if maintenance
doesn't pick up.

diff --git a/bindings/go/.gitignore b/contrib/go/.gitignore
similarity index 100%
rename from bindings/go/.gitignore
rename to contrib/go/.gitignore

diff --git a/bindings/go/LICENSE b/contrib/go/LICENSE
similarity index 100%
rename from bindings/go/LICENSE
rename to contrib/go/LICENSE

diff --git a/bindings/go/Makefile b/contrib/go/Makefile
similarity index 100%
rename from bindings/go/Makefile
rename to contrib/go/Makefile

diff --git a/bindings/go/README b/contrib/go/README
similarity index 100%
rename from bindings/go/README
rename to contrib/go/README

diff --git a/bindings/go/src/notmuch-addrlookup/addrlookup.go b/contrib/go/src/notmuch-addrlookup/addrlookup.go
similarity index 100%
rename from bindings/go/src/notmuch-addrlookup/addrlookup.go
rename to contrib/go/src/notmuch-addrlookup/addrlookup.go

diff --git a/bindings/go/src/notmuch/notmuch.go b/contrib/go/src/notmuch/notmuch.go
similarity index 100%
rename from bindings/go/src/notmuch/notmuch.go
rename to contrib/go/src/notmuch/notmuch.go