Fix #78 SignUp

This commit does,
   1) Check if user exists with given handle OR email, if the row exists, return proper response.
   2) Insert if there is no row with given handle and email and return <b> name, email and handle </b> of an inserted user.
   3) Optional params are First name, last name, display name, quote,country and avatar url.

Let me know if I should do anything else. For sign in, I should use <b> passport </b> and log in the user.