Separate `app-starter` from examples

[JakobMiksch]

relates to #265 and #272

quote from @fschmenger in #265:

IMO adding further code to the app-starter folder for demonstration purpose is not a great solution. This will overload the templates on the long run, which are primarily used for bootstrapping your application. What do you think about refactoring things in the following way:

- wegue
 - app-starter
 - examples
    - projected
    - sidebar
    - custom_module
    - map_overlay
    - vector layer configuration examples ... 
    - further stuff ...

I propose to resemble the folder structure we have under app-starter for all the specific examples. app-starter itself will be stripped down to only contain a single app-conf (maybe even just the minimal one?!). All specific static resources (e.g. shops-dannstadt.geojson, 2012_Earthquakes_Mag.kml, etc.) will be moved to the respective examples they are used for. Then a user could run the examples e.g. by an app-init script in a similar fashion like we do now. Quite a bunch of work but probably more future proof :)

[fschmenger]

This should be on hold, until we have implemented #276. If you agree mark it as a blocker please.

[JakobMiksch]

currently we do not have the concept of "blocker" tags yet. But we can introduce that

[fschmenger]

My bad. I thought Github had some dependency management between issues, such as you could mark "A as blocked by B". But apparently that's not the case. "Blocker" is a little bit confusing, I would rather label this one "blocked" because #276 is the potential blocker :)

[JakobMiksch]

I changed it to 'blocked'