Add Android Downloads and Usage to Statistics

[nicolae-stroncea]

Would be great to also track metrics on:

1. Mobile Downloads
2. Mobile Usage
3. Other Stats that Google gives access to

[ErikBjare]

I can't find a way to export it (much less do so automatically), but here's a screenshot.

Note that the latest release seems to have fixed basically all crashes (fixed in this PR: ActivityWatch/aw-android#42).

[nicolae-stroncea]

That's great to hear about the crashes. In my experience aw-android has been rock-solid both in testing and actual usage. I'm on Android 9(older device) so wasn't affected by the crashes.

I wonder why those users deleted AW and what would have kept them on board

[ErikBjare]

@nicolae-stroncea I wondered about that too, and I'm guessing the very in-your-face "early version" disclaimer start screen leads to a lot of people immediately uninstalling as they realized it's not for them (yet).

It'll be interesting to see how those stats change once we remove the screen.

[rasdani]

I can take at shot at this :)
using this
https://support.google.com/googleplay/android-developer/answer/6135870#export
https://cloud.google.com/storage/docs/gsutil