Refactor frontend routing

[smacker]

Initially, frontend routing was implemented only for 2 pages without clear vision what would be required later (like permission checks).

Now when we have ~10 pages already, it works but requires too much boilerplate copy-past code. We need to improve it.

As a minimum to implement here:

• [ ] router Fragments should be generated automatically based on routes spec
• [ ] custom code on top of redux-little-router should be covered by unit tests

Few more ideas:

• make research on existing libs once again, maybe I missed something that fits our needs the first time
• simplify router middlewares (as an options remove them completely and replace by one middleware with rules provided by routes spec)
• extract custom code to separate folder/package which provides a limited interface. Then use it in the source code of the app