Add basic Session page view

Includes game name, played date, and list of players (and their placing).

Can view at `/sessions` url.

Working on the create page next. In the meantime, here is some sample code to insert 2 sessions with 2 players each (assumes you have 2 players and 2 games with ids 1 and 2).

    --insert session
    INSERT INTO sessions (played, notes, game_id, created_at, updated_at) VALUES
    ('2014-11-04', 'notes went here', 1, '2014-11-04', '2014-11-04');
    --player 1 came in first and on team 2
    INSERT INTO session_players (score, "placing", team_number, player_id, session_id, created_at, updated_at) VALUES
      (11, 1, 2, 1, 1, '2014-11-04', '2014-11-04');
    --player 2 came in second and on team 2
    INSERT INTO session_players (score, "placing", team_number, player_id, session_id, created_at, updated_at) VALUES
      (11, 2, 2, 2, 1, '2014-11-04', '2014-11-04');
    --insert session
    INSERT INTO sessions (played, notes, game_id, created_at, updated_at) VALUES
    ('2014-11-01', 'more test notes?', 2, '2014-11-01', '2014-11-01');
    --player 1 came in second and on team 1
    INSERT INTO session_players (score, "placing", team_number, player_id, session_id, created_at, updated_at) VALUES
      (11, 1, 2, 1, 2, '2014-11-01', '2014-11-01');
    --player 2 came in first and on team 1
    INSERT INTO session_players (score, "placing", team_number, player_id, session_id, created_at, updated_at) VALUES
      (11, 2, 2, 2, 2, '2014-11-01', '2014-11-01');