Web app + db experience

[leaht17]

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From our user studies, @fiveisprime and I have found that customers would like and benefit from an in-line experience with connecting a db when creating a web app.

We'd like to add a prompt to the end of the current web app creation process, like this: Selecting 'Create new database' would kick off the current db creation process. At the end, users would be notified of the web app creation and db connection, like this; Full concept mocked up here.

Also, this shouldn't be dependent on the Databases extension.