Do not add CNAME grunt warning for manual deployment type

This prevents `grunt.warning` for missing CNAME if `options.deployType` is set to `manual`. 

As `manual` is only uploading a new version to the application there is no need to provide a CNAME.
Would it make more sense to not even have this check happen & not have any output when we hit this & are deployType manual? It seems like there's no point in showing the message to the user at all.