build: implement a framework for starting test servers during tests

Test servers are implemented by docker containers and run real servers
for rclone to test against.

fstest/testserver/init.d/README.md

@@ -0,0 +1,31 @@
+This directory contains scripts to start and stop servers for testing.
+
+The commands are named after the remotes in use.  They should be
+executable files with the following parameters:
+
+    start  - starts the server
+    stop   - stops the server
+    status - returns non-zero exit code if the server is not running
+
+These will be called automatically by test_all if that remote is
+required.
+
+When start is run it should output config parameters for that remote.
+If a `_connect` parameter is output then that will be used for a
+connection test.  For example if `_connect=127.0.0.1:80` then a TCP
+connection will be made to `127.0.0.1:80` and only when that succeeds
+will the test continue.
+
+`run.bash` contains boilerplate to be included in a bash script for
+interpreting the command line parameters.
+
+`docker.bash` contains library functions to help with docker
+implementations.
+
+## TODO
+
+- sftpd - https://github.com/panubo/docker-sshd ?
+- openstack swift - https://github.com/bouncestorage/docker-swift
+- ceph - https://github.com/ceph/cn
+- other ftp servers
+