Create way to see other registered users in dummy app + add as friend.

[quantuminformation]

I think this functionality would be useful to others who are using parse to build a social network. Also will be nice to how many people are using this demo app to sign up.

As an extra it would be nice to add these as a friend when logged in and see who you have as a friend.

[quantuminformation]

I've addressed the beginning of this in my pull request.