Add badge label for buttons

[ks-simakov]

I've added an ability to set up badge text for every button and customize this label. I've also added an ability to get current view controllers stack

[ezescaruli]

@GigabyteTheOne This PR is good, I really apologise for the delay!

If you can have a look at the comments I wrote and fix those things, that would be awesome. I'll merge it afterwards. Thanks!