Additional instructions to enable analytics and models

[bsekachev]

My actions before raising this issue

• Read/searched the docs
• Searched past issues

Possible Solution

Instructions to deploy a model now implemented as a github link on empty models page. We might do this page visible by default (event if django models app is not installed). Need to introduce something for analytics.

Context

Need to provide some instructions in CVAT UI to enable analytics and models when these apps are disabled.
It would allow our users get to know that these features exist even if they are deactivated.
The issue is related with #2192

Your Environment

• Git hash commit (git log -1): f2c84a2
• Docker version docker version (e.g. Docker 17.0.05): N/A
• Are you using Docker Swarm or Kubernetes? No
• Operating System and version (e.g. Linux, Windows, MacOS): N/A
• Code example or link to GitHub repo or gist to reproduce problem: