cfg_default: coding style changes
backend exec: wait for it to run, add such config option
app_front: consistent app nw i-face; check_versions()

* encapsulate more nw-specific parts in `app`
* after start or restart check_versions() updates current versions
  of software and possibly node_modules
new controllers: `Base` and `Main`; desktop.Status: backendTools file; dynamic versions

* new controllers: `Base` and `Main`
* move `App.view.desktop.backendTools` to its file
* make versions of tools && libs being used actual
  and dynamic(if they are reload) using new controllers