The Session::reset closes main window, when window was renamed

[aik099]

How to reproduce:

1. start a session either by calling the Session::visit
   • an empty window is opened with an empty window.name (because no URL is opened yet)
   • initial window handle becomes w3cwh:{selenium_window_handle_here}
   • the page URL is visited
   • the page sets it's window.name to the desired value
2. open some other popups from that page
3. call the Session::reset:
   • the Session::swithToWindow() works correctly, because it uses selenium-handle-based window identifier
   • code, that cycles through the opened windows isn't identifying an initial window (because it has a different name) and such and is closing it

For now the only option, that might work is to consider 1st opened window as initial (the 1st window handle returned) and never close it.

Related issue: #26