Merge branch 'plain-readme' into 'master'

Properly render plain readme

## Before

![Screenshot_2015-07-09_11.38.16](https://gitlab.com/gitlab-org/gitlab-ce/uploads/ba53ad380060eba368aed4ecc71ff4da/Screenshot_2015-07-09_11.38.16.png)

## After

![Screenshot_2015-07-09_11.37.38](https://gitlab.com/gitlab-org/gitlab-ce/uploads/b154c5464c3f89d3ed7a0e7157ee6c58/Screenshot_2015-07-09_11.37.38.png

)

cc @rspeicher

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

See merge request !945