update insert command to return an InsertResult instead of a boolean.
Change the return value from boolean to InsertResult
The insert function in MySql returs now a InsertResult instead of a boolean.
This is necessary because we don't just need to know that one row was affected, but also which is the new id for the inserted row.
We need this in order to continue with the implementation for the waitinglist applicants.
Edited by Alexandre Soler Sanandres