mruby: Wrap grn_scan_info_set_op() and grn_scan_info_set_end() in ruby method
Merge pull request #117 from wanabe/mruby-grn_scan_info_set_op-and-end

Wrap grn_scan_info_set_op() and grn_scan_info_set_end() in ruby method

Patch by wanabe. Thanks!!!