Add setting for primary email holder when sharing email addresses

Kinda wordy, but not sure how to shorten without losing clarity. Input welcome.

![screen shot 2014-09-23 at 10 31 24 pm](https://cloud.githubusercontent.com/assets/669/4383190/60096e04-439b-11e4-981b-d9355ec471a9.png)

Line is too long. [124/120]