Added missing gridHeight property

Author: Mek7

ui-grid/ui-grid.d.ts

@@ -489,6 +489,10 @@ declare module uiGrid {
          * returns the total footer height gridFooter + columnFooter
          */
         footerHeight?: number;
+        /**
+         * returns or sets grid height in pixels
+         */
+        gridHeight?: number;
         /**
          * set to true when Grid is scrolling horizontally. Set to false via debounced method
          */