Added Ability to Deploy to a Specific Virtual Directory

Added a command line argument to allow targeted deployment to a specific virtual directory. The new argument is /s or /SiteName followed by the name of the virtual directory to deploy to. This supports the scenario where a single web role is hosting multiple virtual applications, such as a web site and its corresponding API.

Example Usage:
.\WAWSDeploy.exe "_PublishedWebsites\Subdirectory" "mysite.azurewebsites.net.PublishSettings" /s "API"