Select files with diff filter for graph log

It prevent some commit's log has not engough lines.

When a commit has nothing changed, there is only 3 lines log for it,
formatting would not work.
Version 2.1.1
Merge pull request #12 from sugarmo/master

Select files with diff filter for graph log
Better parse of deleted lines
Fixed JSON encoding error

When git's log contain UTF8 code, to_json conver it to wrong string
with ���
Merge pull request #14 from sugarmo/master

Fixed JSON encoding error
Update to latest github-linguist
try to fix default branch selection
Merge pull request #5 from 1ed/master

Try to fix default branch selection
Fixed Compare logic

* Compare show right diff now
* Give right names to some variables
Version 2.2.0
Set date on gem build
fixed a bug that caused non-empty projects to appear empty in some cases

rotated two lines in lib/gitlab_git/repository.rb
the method `raw` needs @path_with_namespace,
so `raw.head.name` should not be executed before `@path_with_namespace = path_with_namespace`
Merge pull request #16 from origsun/master

fixed a bug that caused non-empty projects to appear empty in some cases
Merge pull request #15 from axilleas/update

Update to latest github-linguist
Consider 'ref' when working
Merge pull request #7 from zzet/patch-2

Consider 'ref' when working for graph page
Version up to 2.3.0
Revert linguist update
Refactored Git::Repository