All TabBar views mounted on initial render

[kesha-antonov]

Hello!

In v2. TabBar scenes called componentDidMount only when the tab was focused. Now all of them gets mounted in the same time.

For example:

TabBar
  Tab1
  Tab2
  Tab3

When I go to Tab1 - Tab2 and Tab3 will mount so we have 3 calls to api at the same time.

Maybe I'm missing something? Please advise.

[aksonov]

Please always search existing issues first. Duplicate of #372

[kesha-antonov]

Thanks! @aksonov