Setup Performance testing for the Proxy Server

[BryceStevenWilley]

Figure out:

• Where to put the tests
• when / how to run them
• document how to handle failures, etc.

Tests include:

• General HTTP load, etc.
• Ensure we don't have OOM errors on big XMLs (i.e. continuous verification of Iterator over CodeListDocument XML #330 / Don't load entire codes XML into memory #114)