Merge pull request #995 from nivin-studio/2.0

修复：form表单中的number组件文本内容为空时点击加减按钮出现NaN

resources/assets/dcat/plugins/number-input/bootstrap-number-input.js

@@ -47,10 +47,10 @@
 
             var group = $("<div class='input-group'></div>");
             var down = $("<button type='button'>-</button>").attr('class', 'btn btn-' + settings.downClass).click(function () {
-                setText(parseInt(clone.val()) - 1);
+                setText(parseInt(clone.val() || clone.attr('value')) - 1);
             });
             var up = $("<button type='button'>+</button>").attr('class', 'btn btn-' + settings.upClass).click(function () {
-                setText(parseInt(clone.val()) + 1);
+                setText(parseInt(clone.val() || clone.attr('value')) + 1);
             });
             $("<span class='input-group-btn'></span>").append(down).appendTo(group);
             clone.appendTo(group);