auth_db dbtext Making email address optional so kamctl can support dbtext

Reported by Alberto Sagredo

utils/kamctl/dbtext/kamailio/subscriber

@@ -1 +1 @@
-id(int,auto) username(string) domain(string) password(string) ha1(string) ha1b(string) email_address(string) rpid(string,null) 
+id(int,auto) username(string) domain(string) password(string) ha1(string) ha1b(string) email_address(string,null) rpid(string,null)