Users can send pitch emails to journalists

Trello card: https://trello.com/c/rtMxACiY/56-send-pitch-emails

![email](https://cloud.githubusercontent.com/assets/4560985/5252379/231d97e4-796b-11e4-9ca1-a6e224eca4be.gif)

I'd like to see this extracted to a private so that these three lines all have the same feel to them. End goal of:

``` ruby
pitch = build_pitch(journalist_id)
create_pitch_topics(pitch)
send_pitch_email(journalist_id)
```