added default unit parameter to settings

src/ImageEditor.js

@@ -24,7 +24,9 @@ function ImageEditor(canvasId, args) {
         dimensions: {
             width: 800,
             height: 600
-        }
+        },
+        // Default unit
+        unit: 'cm'
     }, args);
 
 
@@ -83,14 +85,14 @@ function ImageEditor(canvasId, args) {
      * Crops image to desired dimensions
      * @param  {int} width  [description]
      * @param  {int} height [description]
-     * @param  {string} units cm|inch
+     * @param  {string} unit cm|inch
      * @return {ImageEditor}
      */
-    this.crop = function (width, height, units) {
-
+    this.crop = function (width, height, unit) {
+        unit = typeof unit !== 'undefined' ? unit : _settings.unit;
         _canvas.getImageData().removeCropData();
 
-        _canvas.getViewport().set(width, height, units);
+        _canvas.getViewport().set(width, height, unit);
 
         var shouldBeCropped = util.isAspectChanged(_canvas.getImage().width, _canvas.getImage().height, width, height);