Provide option to be mentioned in proxy invite tweets

[dallasjc]

Add a second box with "Your Twitter @username (optional)" for text

Change text to "They'll be sent an invitation tweet and you'll be mentioned if you provide your Twitter username."

Change tweet text when username provided to: .@iamjohnoliver, @democracytrend and 60 other people now want you to represent them in Congress:

This will make it more interactive and easier for people to retweet and hopefully seem more real to the recipients.

[dsernst]

Yeah, that could be good