fix route: Api's namespace
split tweets/_tweet template
don't render status code on error page
show reply tree on tweets/show (single tweet page)
apply rot's new web design
rename user page in tweets controller (best -> user_best, timeline -> user_timeline)
fix pagination: can't render page 2 or later in user_discoveries
Merge branch 'new_design'

Conflicts:
	app/views/tweets/user_favorites.html.haml
	app/views/tweets/user_retweets.html.haml
update README.md, add LICENSE.txt