Remove a deprecated feature of GitLab
Fix a broken reference

b4c27f5d removed the Translation section from README.asc
Add a link to contributing.md

ref https://github.com/progit/progit2/pull/194#issuecomment-64820254
Tweak the sentence

ref https://github.com/progit/progit2/pull/179#issuecomment-64820938
Merge pull request #179 from harupong/remove-gitlab-walls

Remove a deprecated feature of GitLab
Merge pull request #194 from harupong/readme-correction

Fix a broken reference
The
Correct minor typo in paragraph
Merge pull request #198 from amacfie/patch-1

Correct minor typo in paragraph
Merge remote-tracking branch 'upstream/master'

Conflicts:
	README.asc
	book/04-git-server/sections/gitlab.asc
	book/05-distributed-git/sections/contributing.asc