update examples scripts, replacing add_to_server() with two-line statement

note that due to the usage of the 'server' global, it will not work to add a
Session.add_to_server() or core.misc.utils.add_to_server() function
(Boeing r1828)

daemon/examples/netns/iperf-performance-chain.py

@@ -23,17 +23,6 @@ from core.constants import *
 # node list (count from 1)
 n = [None]
 
-def add_to_server(session):
-    ''' Add this session to the server's list if this script is executed from
-    the core-daemon server.
-    '''
-    global server
-    try:
-        server.addsession(session)
-        return True
-    except NameError:
-        return False
-
 def main():
     usagestr = "usage: %prog [-h] [options] [args]"
     parser = optparse.OptionParser(usage = usagestr)
@@ -64,7 +53,8 @@ def main():
     start = datetime.datetime.now()
 
     session = pycore.Session(persistent=True)
-    add_to_server(session)
+    if 'server' in globals():
+        server.addsession(session)
     print "creating %d nodes"  % options.numnodes
     left = None
     prefix = None