Update installation.md

Updating docs to reflect current install steps
Update installation.md
Merge pull request #206 from SteveRyherd/master

Updating docs to reflect current install steps.
Fixed installation docs
Fix adding runner to project
Merge branch 'master' of github.com:gitlabhq/gitlab-ci
Merge branch 'master' into 3-0-stable

Conflicts:
	doc/installation.md