Add forums, topics and posts; add breadcrumbs; style css

1. Add forums which have topics and posts 
2. Add pagination with kaminari
3. Add breadcrumbs with gretel
4. The files in stylesheets/refills I didn't write, so in the interest of your time you might not care to review that
deep merge lets you access a hash within a hash. in my case post_attributes was nested in topic so I couldn't do a regular merge. that's why i used deep merge. its issue I was having last night and this was the solution that i came up with