Pretzel on azure arg

This PR contains a little more than I would like, but it is all related.

1. Command line args all cleaned up, now reports argument extensions properly (like vDir and now --azure) against the right command. Did this by extending the `IHaveCommandLineArgs` interface
1. Also made the help a bit nicer, see below
1. Introduced new interface `IAddtionalIngredient` which can be 'Mixed in' when creating the site. Tests added.


        starting pretzel...
        Usage:
        Pretzel.exe command [options]

              --help                 Display help mode
              --debug                Enable debugging

        Command: bake
          -t, --template=VALUE       The templating engine to use
          -d, --directory=VALUE      The path to site directory
          -p, --port=VALUE           The port to test the site locally
              --vDir=VALUE           Rewrite url's to work inside the specified
                                       virtual directory

        Command: import
          -i, --import=VALUE         The import type
          -f, --file=VALUE           Path to import file

        Command: create
          -t, --template=VALUE       The templating engine to use
          -d, --directory=VALUE      The path to site directory
              --azure                Enables deploy to azure support

        Command: taste
          -t, --template=VALUE       The templating engine to use
          -d, --directory=VALUE      The path to site directory
          -p, --port=VALUE           The port to test the site locally
              --nobrowser            Do not launch a browser
              --vDir=VALUE           Rewrite url's to work inside the specified
                                       virtual directory