Modified logic to handle back button

Modified logic to handle back button also by page name, not just page
number.
This was done to prevent people from going back in different stages of
the game:
State 1 - the bid page (more of a logic difficulty than user related -
poses a problem model wise, the model is not "there" anymore).
State 2 - the bid result page (in cases where the user goes back from
bid result - the user made a bid and wants to change it)