Proxy Support -- Add to user's guide

[GoogleCodeExporter]

If you are having trouble getting this tool to work from behind a http proxy, 
you might want to try setting the proxy options on the command line prior to 
launching the jar file. This information should be added to the User's Guide.  
I figured this out after reading: 
https://developers.google.com/gdata/articles/proxy_setup

Our corporate apps domain requires us to access our sites via https.  This 
example is for https with a proxy host name your-proxy-host.com, port 1080

java -Dhttps.proxyHost=your-proxy-host.com -Dhttps.proxy
Port=1080 -jar google-sites-liberation-1.0.4.jar

Tested on windows7

Original issue reported on code.google.com by [email protected] on 26 Sep 2012 at 10:30