Add analytics tracking to the app

[brafdlog]

Add basic analytics so we know how many users are using the app and how often

[baruchiro]

Is it can be done with Sentry #147?

Also please note that because our app is very sensitive, I think we have to be very open. It's mean that in this case, for example, I don't want to hide this data collection from the user. If the user will find out that we are collecting a piece of information without declaring it clearly, he might stop trusting us.

[baruchiro]

Also, we need to add analytics to landing page #146, to know the relation between users exposed to our app and users that chose to download it.