Fix rubyvis dependency in gemspec
Fix rubyvis dependency in gemspec

mikecmpbll/statsample,michaelphines/statsample,v0dro/statsample,michaelphines/statsample,IsmailM/statsample,IsmailM/statsample,v0dro/statsample,v0dro/statsample,michaelphines/statsample,SciRuby/statsample,IsmailM/statsample,SciRuby/statsample,mikecmpbll/statsample,mikecmpbll/statsample