Added `wait_for_nothing_visible_to_be_animating` for UIRefreshControl animation issue

[samst0r]

Added wait_for_nothing_visible_to_be_animating helper method which checks for views that are animating and are also FEX_isVisible.

This resolves the issues with the UIRefreshControl (Issue #266).

[seanoshea]

+1 to this.

[moredip]

Thanks for the contribution. I'm not sure I like the approach of making two separate frankly_map calls and then zipping the two sets of views together. It assumes that the same set of views will come back, in the same order. That won't happen in all cases (e.g. while a screen transition is happening).

Could you approach this by adding an FEX_isAnimatingAndVisible method on the objective C side so that you could just do something like:

def wait_for_nothing_visible_to_be_animating( timeout = false )
    wait_until :timeout => timeout do
      !element_exists('view FEX_isAnimatingAndVisible')
    end
  end

[samst0r]

No worries. I'll go ahead and add that into ObjC side. That's a good shout.