Add a "Back to List" link when at the DetailsPlace.

Add a "Back to List" link when at the DetailsPlace.

* src/main/java/org/glom/web/client/activity/ListActivity.java:
Populate the CellTable based on the selected table of the ListBox if
it's set otherwise use the default table. This allows the "Back to
List" link to work.
* src/main/java/org/glom/web/client/activity/TableSelectionActivity.java:
Remove Place from constructors. Add a setPlace() method. Add
goToPlace() method. Set class as presenter for TableSelectionView.
* src/main/java/org/glom/web/client/mvp/TableSelectionActivityMapper.java:
Use the same TableSelectionActivity when switching between the List and
Details Places.
* src/main/java/org/glom/web/client/place/DetailsPlace.java:
Subclass the new HasSelectableTablePlace. This removes some duplicate
code.
* src/main/java/org/glom/web/client/place/HasSelectableTablePlace.java:
New class to represent Places that display the TableSelectionView.
* src/main/java/org/glom/web/client/place/ListPlace.java:
Subclass the new HasSelectableTablePlace. This removes some duplicate
code.
* src/main/java/org/glom/web/client/ui/TableSelectionView.java:
* src/main/java/org/glom/web/client/ui/TableSelectionViewImpl.java:
Add Presenter interface. Add setBackLinkVisible() method. Add
setBackLink() method.