Changing account_id default type

After users click on confirmation email to validate themselves, API currently fails with:

```ERROR com.ushahidi.swiftriver.core.api.controller.AbstractController - org.springframework.orm.hibernate3.HibernateJdbcException: JDBC exception on Hibernate data access: SQLException for SQL [n/a]; SQL state [HY000]; error code [1364]; Field 'account_id' doesn't have a default value;```

This should fix it
(Sorry for the other updates - my editor fixes trailing whitespaces automatically)