Show test coverage results in MR if available

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'show-build-coverage-in-mr' into 'master'

Show build coverage in MR

![Screenshot 2014-10-02 18.20.53](https://dev.gitlab.org/uploads/dzaporozhets/gitlabhq/a8ff7b23bd/Screenshot_2014-10-02_18.20.53.png)

See merge request !1148