Improved install script for packaged telegraf:

* Start/stop service on Debian/Ubuntu
* Disable init-script/Systemd-unit on package removal

closes #747

scripts/pre-remove.sh

@@ -0,0 +1,15 @@
+#!/bin/bash
+
+BIN_DIR=/usr/bin
+
+# Distribution-specific logic
+if [[ -f /etc/debian_version ]]; then
+    # Debian/Ubuntu logic
+    which systemctl &>/dev/null
+    if [[ $? -eq 0 ]]; then
+	deb-systemd-invoke stop telegraf.service
+    else
+	# Assuming sysv
+	invoke-rc.d telegraf stop
+    fi
+fi