Bounty 390 comments markup

**Bug:** https://assembly.com/coderwall/bounties/390#
**Description:** Navigating to `/p/PROTIP_ID/comments` generates ugly markup

Changes:
1. Added import of existing admin css styling to application.css.scss
2. Added comments header and icon like on protip page
3. Add comments header and icon styling

![coderwall com establishing geek cred since 1305712800](https://cloud.githubusercontent.com/assets/5670940/4550478/1387c63a-4e67-11e4-9304-6a8db57c44fc.png)