Email verification on signup

[dongyuzheng]

Very similar to https://github.com/rezqio/issues/issues/4

1. Modify gql schema for email signup to have is_active = False
   • Send verification email, using our JWT library to create some verification token (payload signup_email_user_id, expiry 90 minutes)
2. Modify rezq.mixins.auth_mixin.AuthMixin to check if user is_active
   • Return HttpResponseUnauthorized() if not active
3. Modify rezq.api.v1.schemas.token.CreateToken to check if user is_active
4. Create new endpoint (probably inside profile.py) to handle this verification token to set is_active = True