testserver: Make Test{FTP,SFTP,Webdav}Rclone run the current rclone

Before this change the tests were run against the previous stable
rclone/rclone docker image.

This unfortunately masked errors in the integration test server.

This change uses the currently installed rclone to run "rclone serve
ftp" etc. This is installed out of the current code by the integration
test server so will make a better test.

fstest/testserver/init.d/rclone-serve.bash

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# start an "rclone serve" server
+
+PIDFILE=/tmp/${NAME}.pid
+DATADIR=/tmp/${NAME}-data
+
+stop() {
+    if status ; then
+        pid=$(cat ${PIDFILE})
+        kill $pid
+        rm ${PIDFILE}
+        echo "$NAME stopped"
+    fi
+}
+
+status() {
+    if [ -e ${PIDFILE} ]; then
+        pid=$(cat ${PIDFILE})
+        if kill -0 &>1 > /dev/null $pid; then
+            # echo "$NAME running"
+            return 0
+        else
+            rm ${PIDFILE}
+        fi
+    fi
+    # echo "$NAME not running"
+    return 1
+}
+
+run() {
+    if ! status ; then
+        mkdir -p ${DATADIR}
+        nohup "$@" >>/tmp/${NAME}.log 2>&1 </dev/null &
+        pid=$!
+        echo $pid > ${PIDFILE}
+        disown $pid
+    fi
+}
+
+. $(dirname "$0")/run.bash