Update highscores.py to move to is_high_score()

Is_high_score() returns True or False to the caller to let them know if the score is really a new high score.  Often the caller wants to notify the user of their achievement and congratulate them.  We also now check the initial score to ensure that it is numeric.
Merge pull request #1 from cclauss/patch-1

Update highscores.py to move to is_high_score()