create deploy_to before trying to copy files to it

this fixes the following issue:

when you want to deploy a new app with `deploy:setup` and the `deploy_to` directory does not exist, it throws an error because the `deploy_to` directory does not exist. this happens because `gemrc` task runs before `deploy:setup`. this fix creates the directory. another solution would be, to run `gemrc` task not before but after `deploy:setup`.