`estimatedRowHeight = UITableViewAutomaticDimension` not enough for iOS8/9

[fmaylinch]

With the iOS7+ version of this piece of code running in iOS8/9, I get lots of layout conflicts and calls to heightForRowAtIndexPath for every row, so I merged both versions:

    if #available(iOS 8.0, *) {
        rowHeight = UITableViewAutomaticDimension
        estimatedRowHeight = 400
    } else {
        estimatedRowHeight = UITableViewAutomaticDimension
    }

I don't think this is related, but I also had to use this solution to avoid layout conflicts. I think it's necessary when the default height of 44 is not enough to fit your views initially (for example if you are add a constraint like "V:|-[v(100)]-|").

With both changes, I get it working without layout conflicts. Thanks!