Use cursor mode in the query that gets data for the list view.

Use cursor mode in the query that gets data for the list view.

I still need to fix the potential memory problem when getting the row
count for the list view.

* TODO: Add note about testing memory usage with large data sets. Add
item about fixing row counting with large data sets.
* src/main/java/org/glom/web/server/OnlineGlomServiceImpl.java: Put the
PostgreSQL JDBC driver into cursor mode when getting data for the
list view.