xenapi: Pass string arguments to popen

The current BitTorrent code was passing integer arguments to `make_subprocess`
which would in turn pass those to `popen`. This would cause a failure because
the semantics of the underlying `execve` function is to only accept a list of
strings.

The solution is to cast the arguments to a string before passing them into
`make_subrpocess`.

Fixes bug 1201594

Change-Id: I8372795ca032420641c449cb07bb47f9252ff4ef

plugins/xenserver/xenapi/etc/xapi.d/plugins/bittorrent

@@ -169,9 +169,9 @@ def _seed(torrent_path, seed_cache_path, torrent_seed_duration,
           torrent_listen_port_start, torrent_listen_port_end):
     plugin_path = os.path.dirname(inspect.getabsfile(inspect.currentframe()))
     seeder_path = os.path.join(plugin_path, SEEDER_PROCESS)
-    seed_cmd = [seeder_path, torrent_path, seed_cache_path,
-                torrent_seed_duration, torrent_listen_port_start,
-                torrent_listen_port_end]
+    seed_cmd = map(str, [seeder_path, torrent_path, seed_cache_path,
+                         torrent_seed_duration, torrent_listen_port_start,
+                         torrent_listen_port_end])
     utils.run_command(seed_cmd)