[#1640] Use same connection in order to apply all DB evolutions

The evolutions plugins open a new connection in order to execute each SQL lines stored in one evolution file. This behavior works with DDL SQL orders but failed with DML SQL like this : 

insert into mytable values(nextval(mysequence), 'field1');
insert into my_linked_table values(currval(my_sequences), 'another_field_value');

In this example, we used sequence functions 'currval' and 'nextval' to get the sequence value. It's failed because the Evolutions plugins uses two JDBC connections.

Regards,
Jérôme BENOIS