Add support for accessing multiple glom documents in the servlet.

Add support for accessing multiple glom documents in the servlet.

This completes the demo selection functionality.

* src/main/java/org/glom/web/client/OnlineGlomService.java: Add
document title to methods.
* src/main/java/org/glom/web/client/OnlineGlomServiceAsync.java: Add
document title to methods.
* src/main/java/org/glom/web/client/activity/DemoSelectionActivity.java:
Set browser window title when the activity starts. Correct name of
document title variable.
* src/main/java/org/glom/web/client/activity/OnlineGlomActivity.java:
Set browser window title when the activity starts. Set the table
selector change handler after table selector has been set. Clear the
OnlineGlomView when the activity has been stopped.
* src/main/java/org/glom/web/client/place/OnlineGlomPlace.java: Use the
document title as the place token. Use "#Document:" instead of
"#OnlineGlomPlace:" in the URL.
* src/main/java/org/glom/web/client/ui/DemoSelectionViewImpl.ui.xml:
Change heading to "Online Glom"
* src/main/java/org/glom/web/client/ui/LayoutListView.java: Use
document title in RPC methods.
* src/main/java/org/glom/web/client/ui/OnlineGlomView.java: Remove
setDocumentTitle() method. Add clear() method.
* src/main/java/org/glom/web/client/ui/OnlineGlomViewImpl.java: Remove
setDocumentTitle() method. Implement clear() method which removes the
change handler on the ListBox, clears the ListBox and clears the
DataPanel.
* src/main/java/org/glom/web/server/OnlineGlomServiceImpl.java:
Implement methods with document title. Keep track for the configured
glom documents and their corresponding JDBC configurations in a hash
table. This information is retrieved using the document title as the
key in the hash table.
* src/main/java/org/glom/web/shared/GlomDocument.java: Remove
document title field as it's no longer needed.