Added plugin (only for contrib right now) installation script

Updated docs.

bin/plugin

@@ -0,0 +1,61 @@
+#!/bin/sh
+# Install contrib plugins.
+#
+# Usage:
+#     bin/plugin install contrib
+#
+# Figure out if we're using wget or curl
+
+basedir=$(cd `dirname $0`/..; pwd)
+. ${basedir}/bin/logstash.lib.sh
+
+WGET=$(which wget 2>/dev/null)
+CURL=$(which curl 2>/dev/null)
+
+URLSTUB="http://download.elasticsearch.org/logstash/logstash/"
+
+if [ "x$WGET" != "x" ]; then
+	DOWNLOAD_COMMAND="wget -q --no-check-certificate -O"
+elif [ "x$CURL" != "x" ]; then
+    DOWNLOAD_COMMAND="curl -s -L -k -o"
+else
+	echo "wget or curl are required."
+	exit 1
+fi
+
+
+if [ -f "$basedir/lib/logstash/version.rb" ] ; then
+	VERSION=$(cat "$basedir/lib/logstash/version.rb" | grep LOGSTASH_VERSION | awk -F\" '{print $2}') 
+else
+	echo "ERROR: Cannot determine Logstash version.  Exiting."
+	exit 1
+fi
+
+# Placeholder for now, if other installs ever become available.
+if [ "x$2" != "xcontrib" ]; then
+	echo "Can only install contrib at this time... Exiting."
+	exit 1
+fi
+
+TARGETDIR="$basedir/vendor/logstash"
+mkdir -p $TARGETDIR
+SUFFIX=".tar.gz"
+FILEPATH="logstash-contrib-${VERSION}"
+FILENAME=${FILEPATH}${SUFFIX}
+TARGET="${TARGETDIR}/${FILENAME}"
+
+case $1 in
+  install)
+  	exec $DOWNLOAD_COMMAND ${TARGET} ${URLSTUB}${FILENAME}
+  	if [ ! -f "${TARGET}" ]; then
+	  	echo "ERROR: Unable to download ${URLSTUB}${FILENAME}"
+	  	echo "Exiting."
+	  	exit 1
+	fi
+  	gzip -dc ${TARGETDIR}${FILENAME} | tar -xC $TARGETDIR
+  	cp -R ${TARGETDIR}/$FILEPATH/* .  ;; # Copy contents to local directory, adding on top of existing install
+  *) 
+  	echo "Usage: bin/plugin install contrib"
+	exit 0
+	;;
+esac

docs/core-vs-contrib.md

@@ -1,5 +1,5 @@
 ---
-title: Logstash Core and Contrib - logstash
+title: Logstash Core and Contrib
 layout: content_right
 ---
 
@@ -11,7 +11,15 @@ Contrib plugins reside in a [separate github project](https://github.com/elastic
 # Packaging
 At present, the contrib modules are available as a tarball.
 
-# Installation
+# Automated Installation
+The `bin/plugin` script will handle the installation for you:
+
+```
+cd /path/to/logstash
+bin/plugin install contrib
+```
+
+# Manual Installation (if you're behind a firewall, etc.)
 The tarball build defaults to extract on top of an existing Logstash tarball installation. 
 For example, if I've extracted `logstash-1.4.0.tar.gz` into `/path`, e.g.
 
@@ -34,25 +42,4 @@ cd /path
 tar zxf ~/logstash-contrib-1.4.0.tar.gz
 ```
 
-This will install the contrib plugins in the same directory as the core install.
-
-# Building contrib
-Building your own contrib plugin collection tarball is important if you wish to 
-add your own custom plugins and then distribute those to your Logstash installations. 
-
-* Clone the repository, e.g. 
-
-```git clone https://github.com/elasticsearch/logstash-contrib.git```
-
-* Checkout the correct version (e.g. v1.4.0) to match your core Logstash installation, e.g.
-
-```git checkout v1.4.0```
-
-* (If you have code or changes to add/remove, make them at this point, if not proceed to 
-  the next step.)
-* Build the tarball package:
-
-```make tarball```
-
-* The resulting `logstash-contrib-${VERSION}.tar.gz` will be in the `build` directory
-
+This will install the contrib plugins in the same directory as the core install.