Markdown: Fix the incorrect autolinking on url.
Markdown: Fix the incorrect autolinking on url.

Currently markdown may misunderstand path segment of url as a link to
an issue or a commit. This fixes the bug by avoiding to make a word
which starts with "http" a link to an issue or a commit.

This fixes #210.

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