Bugfix. While SimpleSAML\Database::query() returns a PDOStatement, SimpleSAML\Database::exec() doesn't. Make both return an integer with the amount of rows affected. Add a return value to SimpleSAML_Metadata_MetadataStorageHandlerPdo::initDatabase().

Created a central database class and updated the PDO MetaDataStorangeHandler to use it instead of its own database classes

Fixed bug with adding metadata where it would try to run an UPDATE against the SQL DB if an entry did not already exist.