Make GeoExplorer work with strict mode
Attempt to add a button to the current add layer dialog window
Add a FormPanel to the add layer dialog instead of adding each form
element by hand

I need to review the catalog search api as it seems to have a lot of
similar functionality.
Attach the search form to the GeoExplorer class

This commit allows us to check to see if the search form has been
already attached to the to GeoExplorer object. This prevents the
search form being added twice.
Add first pass of search in the add layer dialog

This commit adds a new form in the add layer dialog that allows a user
to limit the list of layers by a search parameter.