Suggestion to add Back-end installation steps in Swift and Java sections

The landing pages for swift and java jump directly to the data modeling sections

We need a landing page for each of these platforms that will take users through introduction, backend installation etc first before they jump into the app installation.

Without that context, users will have to idea how to get through the installation.

While I understand unifying the tutorials, I am inclined to just retain the old version of tutorial for the Travel Sample app - unless we can figure out a clean way of getting though each of the paths.