Adding shoutbox feature for user pages and user's dashboard

@cgruppioni @chukdisc

I also know that I'm using _path for many link_tos, but those are all placeholders until I actually use them. Also, wouldn't mind tips on what I should be doing with my divs, classes and ids + css.
Do you mean make it so that the current_user calls the method instead? I'm not sure if you mean I should do shout.user ? I could hasten the search for the shout by using current_user.shouts.find, though.