Add ability to change dialog style to allow alert dialog customizations

[meets7]

This allows the ability to change alert dialog style and also provides the ability to set status bar color. Can even be set to transparent to allow and draw behind without translucency.

Before:

After:

Usage:

  viewer = StfalconImageViewer.Builder<Poster>(this, Demo.posters, ::loadPosterImage)
      .withStartPosition(startPosition)
      .withHiddenStatusBar(false)
      .shouldStatusBarTransparent(true)
      .withDialogStyle(R.style.MyCustomStyle)
      .show()