Host social

Updates #96 

- [x] adds `facebook` and `twitter` fields to users
- [x] adds validations for the fields
- [x] adds form fields to account settings for facebook and twitter fields
- [ ] adds icons to user profile page
@ankitshah811 The user account edit page is the same regardless of your role. Should this be nested under a conditional that checks if the user is a Host before displaying these things? And should we have validations on the server side that don't allow non Hosts to update their social accounts?