a few incremental updates

- adding guest additions
- adding a few extra sync's to zero blocks
- adding space to wget to avoid history
- adding offline directory and teaching.mininet.org
- fixing lxterminal defaults and screensaver
diff --git a/onos-build-vm.py b/onos-build-vm.py
index 62bb7e6..75dc322 100755
--- a/onos-build-vm.py
+++ b/onos-build-vm.py
@@ -24,7 +24,7 @@
     # start with sendline
     #TODO consider resizing the HDD
     url = 'https://gerrit.onlab.us/gitweb?p=ONOS-VM.git;a=blob_plain;hb=refs/heads/mininet-tutorial;f=vm-setup.sh'
-    vm.sendline( 'wget -O vm-setup.sh "%s" | bash' % url )
+    vm.sendline( ' wget -O vm-setup.sh "%s" | bash' % url ) # space prefix is used to avoid entry in history
     vm.expect( prompt, timeout=20 )
     vm.sendline( 'bash vm-setup.sh' )
     # end with expect prompt