web: Fix order of preview images in capture screen
web: Fix order of preview images in capture screen

Previously we had ['odd', 'even'], but ['even', 'odd'] is the natural
order from the bookspread.

nafraf/spreads,miloh/spreads,gareth8118/spreads,DIYBookScanner/spreads,nafraf/spreads,adongy/spreads,DIYBookScanner/spreads,gareth8118/spreads,DIYBookScanner/spreads,miloh/spreads,adongy/spreads,adongy/spreads,miloh/spreads,gareth8118/spreads,nafraf/spreads