python: Make the program explicitly tell to outside this is Python version

We'll soon have several helloweb programs written in different languages
with otherwise the same output, and it is better to distinguish them for
diagnostic.

python/helloweb.py

 #!/usr/bin/env python
 """Simple web-server that says "Hello World" for every path
 
-helloweb [--logfile <logfile>] <bind-ip> <bind-port> ...
+helloweb.py [--logfile <logfile>] <bind-ip> <bind-port> ...
 """
 
 import sys
@@ -19,7 +19,7 @@ class WebHello(BaseHTTPRequestHandler):
         self.end_headers()
 
         print >>self.wfile, \
-            "Hello %s at `%s`  ; %s" % (
+            "Hello %s at `%s`  ; %s  (python)" % (
                 ' '.join(self.server.webhello_argv) or 'world',
                 self.path, time.asctime())
 
@@ -41,7 +41,7 @@ def main():
         f = open(args.logfile, 'a', buffering=1)
         sys.stderr = f
 
-    print >>sys.stderr, '* %s helloweb starting at %s' % (
+    print >>sys.stderr, '* %s helloweb.py starting at %s' % (
         time.asctime(), (args.bind_ip, args.bind_port))
 
     # TODO autodetect ipv6/ipv4