Allow proxy to be used and enhance jndi support

I've added the ability to specify a proxyHost and proxyPort to be used for connection to Amazon (needed when running a private EC2 instance).  I've also improved the JNDI support so you can now specify all the required parameters such as endpoints and the new proxy details.  It would be really great to get this in the next release.  Cheers
Andy
Vistair Systems Ltd