Add compelling examples for end users.

[reicheltp]

It would be awesome if the website would contain some complete and compelling examples for users who are new to Cake.

I have something in my mind like:

• Build an Android APK and upload to HockeyApp
• Build a .NET Project with Semantic Versioning and upload artifacts to NuGET
• Run a bunch of Unit Tests and Upload Test Coverage to coverall.io
• ...

The samples could may be loaded from a community maintained repo in the cake-contrib organization. This increase the chance that the examples are always up to date.

[pascalberger]

List of examples showing specific aspects:

• [ ] Preprocessor directives (https://github.com/cake-build/website/pull/1065)
• [ ] How to integrate npm tools into build pipeline (Cake.Module.Npm, Cake.Npm)
• [ ] How to setup a repo using .NET Tool (local manifest, which should be under version control)

[pascalberger]

We also have an example repository: https://github.com/cake-build/example