Enhanced apps management [WIP]

:construction: 

TODO:
* [x] merge Handlebars.js pull request which this depends on https://github.com/owncloud/core/pull/10413
* [ ] add »Recommended« tag to recommended apps (directly next to the score)
* [ ] add link to »More apps in the store …«
* [ ] sort by name (in the future by rating + downloads)
* [ ] make it faster!
Are you sure that this is required? I think using `{{` should work as well here, actually I tested it just right now in Chrome. The point I want to make is that in future we might rely on just searching for `{{{` to find potential security issues and the fewer we have the fewer one need to verify ;-)