Discussion changes

Changes
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- Various discussion style / layout changes (see screenshot)
- Fixed recommend binding multiple times
- Fixed recommend not working for replies that were truncated
- Fixed multiple comment boxes appearing when clicking a reply button more than once
- Show reply button when not signed in and link to signin page

Before
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![image](https://cloud.githubusercontent.com/assets/960919/4504683/c77d2274-4ae9-11e4-9cdf-0b89602eaea4.png)

After
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![image](https://cloud.githubusercontent.com/assets/960919/4504685/de0c19e6-4ae9-11e4-8f85-f52fbcb96377.png)