Add ability to deploy only the Web.config

[peterkeating]

Currently the deployment will deploy everything - Orchard, custom modules & custom themes. Quite often we will change a value in the Web.config, but then have to deploy everything again, which can take a considerable amount of time. Until we've developed a way of doing a calculated rebuild of the deploy-able artefact, it'll be good to only deploy the Web.config file for the site.