Add a refresh button that update the game tree content.

Reported-by: lhguyenduc, bnurbekov
Co-authors:
Long Nguyen Duc Hoang <lhnguyenduc@wpi.edu>
Batyrlan Nurbekov <bnurbekov@wpi.edu>
Merge pull request #258 from hlong290494/refreshBtn

Add a refresh button that update the game tree content