[BACKLOG-256]  Adding a PDIDialect to expose the "Pentaho Data Integrati...

...on" database type in the Connection dialog.  This commit also adds DefaultDatabaseName and DefaultOptions to DatabaseType, since the PDIDialect defines default options of "kettle" for dbname and "webappname=pentaho-di" for an option.  A subsequent commit will update the GWT classes to actually use these values.