code: function(filestring){
          var _sliceObject;
          var _regex = new RegExp('background-image:[\\s]*url\\(["\']?(?!http[s]?|/)[^;]*?(slice[\\w\\d\\s!./\\-\\_@]*\\.[\\w?#]+)["\']?\\)[^;}]*;?', 'ig');
          var _sliceCodeList = filestring.match(_regex);
          var _pathToResource;
          var _sliceImgUrlList = [];
          var _sliceList = [];
          if(_sliceCodeList !== null){
              for(var x=0;x<_sliceCodeList.length;x++){
                  _pathToResource = _sliceCodeList[x].replace(_regex,"$1");
                  _sliceImgUrlList[x] = _pathToResource;
                  _sliceList[_pathToResource] =  _sliceCodeList[x];
              }
          }
          _sliceObject = {
              img:_sliceImgUrlList,
              list:_sliceList
          }
          return _sliceObject;
      }
docs: [_getSliceObjectHandler 根据CSS文件获取图片列表和对应的样式文件]
  @param  {[string]} filestring [转换为string的css文件buffer]
  @return {[object]}            [返回object{img:[],list:[]}]