fix story title truncation in Story

https://twitter.com/LobsterNews/status/331496217286701058 has just a title of "..." but should have included at least a few words from "LibOnionRoute is a fork of the Tor onion router sourcecode to transform it into a linkable library" to still fit in the character limit.

`Status` was checking for `len(status)` instead of the passed `length` variable, and it was also prepending a space before each word even on the first one.

http://play.golang.org/p/cfG6a7bYWd