Disables multiple selection in the tree

Now a user can't select more than one game in the tree

Author: lhunker
Fixes a bug where voting in games without a deck always submitted a vote of 0.
Merge pull request #139 from dbeckwith/diableMultipleSelection

Disables multiple selection in the tree
Merge pull request #140 from dbeckwith/noDeckVoteFix

Fixes a bug where voting in games without a deck always submitted a vote...
Merge branch 'team9dev' into user_bug_fixes