Mention: fix line feed on select list(Mac)
Mention: fix line feed on select list(Mac)

1. change mention.js to 'https://github.com/nforge/Mention.js'
- 558c88b commit by wansoon

ihoneymon/yobi,doortts/forked-for-history,doortts/forked-for-history,doortts/fork-yobi,brainagenet/yobi,ChangsungKim/TestRepository01,doortts/fork-yobi,ahb0327/yobi,yona-projects/yona,doortts/forked-for-history,oolso/yobi,Limseunghwan/oss,doortts/fork-yobi,bloodybear/yona,bloodybear/yona,brainagenet/yobi,ahb0327/yobi,ahb0327/yobi,ihoneymon/yobi,ChangsungKim/TestRepository01,doortts/fork-yobi,naver/yobi,bloodybear/yona,oolso/yobi,Limseunghwan/oss,ihoneymon/yobi,naver/yobi,brainagenet/yobi,naver/yobi,yona-projects/yona,violetag/demo,bloodybear/yona,yona-projects/yona,oolso/yobi,violetag/demo,yona-projects/yona,Limseunghwan/oss