Trust indicators

Show trust indicator to quickly see if we can "trust" a person. It's based on account creation, link karma and comment karma.

![image](https://cloud.githubusercontent.com/assets/339611/5579297/6f7034ce-9038-11e4-98b0-63dbe838033c.png)

Color and threeshold are configurable.

Exemple of use : you do a contest and want to quickly check if people have an account of at least 1 week old. You want to buy something you can quickly see for which people you should care.

The link/comment karma is global (not subreddit based).

Suggestions : 
Fantasy font family ?
![image](https://cloud.githubusercontent.com/assets/339611/5579314/d0109a94-9038-11e4-81a4-95a774141d8f.png)

Maybe change option name/description ?

Maybe change default color/threeshold ?