(refs #373)Preview markdown in the text file editor.
Fix width styles

* issue updation title and content
* issue new comment
* pull request new comment
(refs #372)Use shift key instead if ctrl key to select region
Merge branch 'master' of https://github.com/takezoe/gitbucket
Repository url protocol label should be change

Like repository url.
Fix style broken in Firefox
Fix title in file editing.
Hide "Edit" button if target is not head of the branch.
Show diff for files other than markdown by "Preview" button
(refs #375)Show merge commit diffs correctly
(refs #346)Add group members as collaborator when transfer repository to the group.