Fixes #55 - game_flow returns the list of games per skill level

    Finished creating workflow views.
    Now the game_flow ca return the list of games per skill level, with a
    boolean attribute that shows if that game is enabled or not,
    depending on game_flow rules.

    Created two types of rules: finished game and partial completion game dependencies.

Fixes #56 - Test cases for enabled and disabled games were created.

    This game list is returned from the gameflow view which needs to be authenticated.
    A login page, copied from admin site, was created for login a user.