Minor fix to chat links; rounded critical hit percentages

Two minor changes:

1. Markdown links in a chat message should open in a new browser tab, but only the first link in a message with multiple links was actually opening in a new tab. Now all chat links open in a new tab.

2. Growl notifications for critical hits were were showing some floating point ugliness, e.g.
![screen shot 2014-01-08 at 3 44 54 pm](https://f.cloud.github.com/assets/1245093/1873805/c0d1cb2a-78bf-11e3-8858-ae8ed497170f.png)
I rounded to an integer
![screen shot 2014-01-08 at 3 50 02 pm](https://f.cloud.github.com/assets/1245093/1873804/c0cf8cca-78bf-11e3-8574-a9227bc90082.png)