New API for working with windows (switching/finding/closing/opening/etc.)
Bugfixing for windows API (primarily switch_to_window and within_window)
Add maximize window
Resize/get size/close should work for non-current window
Fix bug with scopes when within_window is invoked inside within
Also fix intermittent spec failures
Merge pull request #1235 from abotalov/add_methods_for_windows

New API for working with windows (switching/finding/closing/opening/etc....)