Added support for DB2 on AS/400 or ISeries

First push of the modified version of the DB2as400 package

NB: the metadata table must be uppercase or the Table.exists() method won't find it
(perhaps a bug in the JTOPEN JDBC driver ?)

So for instance:
flyway.table=MY_SCHEMA
This lines should be deteled because we didn't need this, I assume It was only for testing Bertrand right?