Add Dark Theme for OGads App

I'm using OGAds app pretty often and I would love to see the same nice gray color we have on our OGAds website.

I see many people are using the app for chatting, not only to check earnings & statistics. So it might be an useful thing, considering a darker theme might also save some battery too.

Also there is a problem with the Statistics tab inside the app. Whenever i click the filters button in the top right corner, the app crashes.