Add document describing how to set up an env for Linux packaging

PKG_LINUX.md

@@ -0,0 +1,60 @@
+# Build RabbitMQ Packages using Linux
+
+
+## Environment
+
+Debian Jesse using this `Vagrantfile`:
+
+```
+$script = <<SCRIPT
+export LANG='C.UTF-8'
+export DEBIAN_FRONTEND=noninteractive
+
+echo 'deb http://httpredir.debian.org/debian jessie-backports main' >> /etc/apt/sources.list.d/backports.list
+
+wget https://packages.erlang-solutions.com/erlang-solutions_1.0_all.deb
+dpkg -i erlang-solutions_1.0_all.deb
+
+apt-get clean
+apt-get update
+apt-get install -y --fix-missing --no-install-recommends \
+	build-essential \
+	ca-certificates \
+	debhelper \
+	dh-systemd \
+	elinks \
+	esl-erlang \
+	elixir \
+	fakeroot \
+	git \
+	libfile-fcntllock-perl \
+	mandoc \
+	nsis \
+	python-lxml \
+	python-markdown \
+	python-simplejson \
+	rpm \
+	rsync \
+	tofrodos \
+	unzip \
+	xmlto \
+	xsltproc \
+	zip \
+	curl
+date > /etc/vagrant_provisioned_at
+SCRIPT
+
+Vagrant.configure('2') do |config|
+  config.vm.box = "debian/jessie64"
+  config.vm.hostname = 'DEBIAN-JESSIE64'
+  config.vm.provision 'shell', inline: $script
+end
+```
+
+## Instructions
+
+Bring up a Debian Jesse instance using Vagrant, or, use the provisioning script
+on a Debian Jesse server of your own. When it is done running, all necessary
+package build requirements for either `apt`-based or `rpm`-based distros will
+be present. See the [`README.md`](README.md#tldr) document for instructions on
+building packages.

README.md

@@ -38,6 +38,10 @@ make package-standalone-macosx
 make -C packaging package-standalone-macosx SOURCE_DIST_FILE=/path/to/rabbitmq-server-3.8.1-rc.1.tar.xz
 ```
 
+The instructions in the [`PKG_LINUX.md`](PKG_LINUX.md) document include a
+script to install the necessary pre-requisites for building package archives as
+well as `deb` and `rpm` packages.
+
 ## Source archive
 
 ### How to create it