def login!(passwd = nil)
      self.password = passwd || self.password
      response = client.login(username.to_s, password.to_s)
      apply_attributes! response.result
      self.session_token.present?
    end
def login!(passwd = nil)
      self.password = passwd || self.password
      response = client.login(username.to_s, password.to_s)
      apply_attributes! response.result
      self.session_token.present?
    end
Login and get a session token for this user.
 @param passwd [String] The password for this user.
 @return [Boolean] True/false if we received a valid session token.