Basic UI implememntation of comments in timeline style

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Fix discussion style for timeline

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Round avatars for notes timeline

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'notes-timeline' into 'master'

Notes timeline

Fixes #1496

![Screenshot 2014-08-26 09.55.27](https://dev.gitlab.org/uploads/gitlab/gitlabhq/07f0eafa78/Screenshot_2014-08-26_09.55.27.png)

See merge request !1023
Merge branch 'master' of github.com:gitlabhq/gitlabhq