JDBC driver link creation moved to postinst to circunvent problems
introduced by old navalplan packages deleting the link when the
package is being removed.
Psql8 does not support altering table permissions using "ON ALL TABLES IN
SCHEMA", so this commit implements a workaround which consists in dumping
the original (and upgraded) database and loading it again, instead of
just doing a rename and fixing permissions afterwards.
FEA: ItEr75S03CommunityMaterial