Fix build

Author: Zamaroth

src/chart.js

@@ -55,7 +55,7 @@ var plugins = [];
 
 plugins.push(
     require('./plugins/plugin.filler')(Chart),
-    require('./plugins/plugin.gridLines')(Chart),
+    require('./plugins/plugin.gridlines')(Chart),
     require('./plugins/plugin.legend')(Chart),
     require('./plugins/plugin.title')(Chart)
 );