###Texting App
Build an app that lets users send text messages to their friends.
-DONE-As a user, I want to send a text message to a phone number, so that I can send texts from the web.
As a user, I want to save contacts to an address book, so that it's easy to text them again without re-typing their phone number.
As a user, I want to send a message to more than one person at once, so that I can mass text my friends.
As a user, I want to send pictures in my messages, so that I can share photos and cute cat pics with my friends. Hint: Check the Twilio API docs.
As a user who receives a text message, if I text back, I want to get an automated response telling me that the phone number can't receive texts, so that I don't get sad when the sender doesn't reply.