Improve performance of initial ListView load.

Improve performance of initial ListView load.

I removed a round trip to the server for getting the default table name
and then requesting information about that table. This also removes a potential
problem with the table change handler not being setup in time to receive the
table change event from the ListActivity.

* src/main/java/org/glom/web/client/OnlineGlomService.java:
* src/main/java/org/glom/web/client/OnlineGlomServiceAsync.java: Add
getDefaultLayoutListTable() method. Improve comments.
* src/main/java/org/glom/web/client/activity/ListActivity.java: Use
getDefaultLayoutListTable() method instead of firing a table change
event to get the table to load.
* src/main/java/org/glom/web/server/OnlineGlomServiceImpl.java: Add
implementation of getDefaultLayoutListTable() method.
* src/main/java/org/glom/web/shared/LayoutListTable.java: Add field for
table name.