Fix 404 error while displaying json files.

It uses params[:id] instead of request.fullpath.
It should fix #3132.
replace Gitolited mixin with Gitlab::ShellAdapter
Move directory logic out of model. Use Gitlab:Shell class to interact with file system
fix commit-description css on commit.show
Move commit.show partial from commits/ to commit/
Dont show '0 additions and 0 deletions' message for commit
Fix style of network graph.

refs #3258
Using arrowed line only if it connects to not first parent.

It is easy to see which branch is merged.
Merge pull request #3288 from hiroponz/fix-style-network-graph

Fix style of network graph.
Fix lines and line numbers being squashed in File -> blame
fix blame view head nav
Change gollum repo to use https:// instead of git://

A lot of people might have firewalls blocking the git:// protocol. Using https:// makes this easier and matches the other git repositories in the Gemfile.
Change Gemfile.lock repo to use https://
Attribution as mentioned in https://news.ycombinator.com/item?id=5423635
Use real name.
fix xss issue in blame
All involved are mentioned. https://news.ycombinator.com/item?id=5424050
Merge pull request #3303 from dosire/attribute

Attribution as mentioned in https://news.ycombinator.com/item?id=5423635
Merge pull request #3300 from aus/patch-1

Change gollum repo to use https:// instead of git://
Update ruby to latest version.