Tweaked profile stream activity entries

I swapped the position of the user's name and the topic title so that it would look more like the below screenshot, and the link targets would make sense (and I wrapped the post # in a link for good measure):

![mock-up of link position change](http://cdn2.discourse.org/uploads/d/f/7789fedd83c1aa59549ab8a8ad4a5442b0207d.png)

The name will also now read "You" if the owning user is yourself, and the avatar will now have the username as a title, instead of the title of the topic.