Added filter by list and pan to selected configuration options

In index.html there are two additional configuration options:
FILTER_LIST_BY_EXTENT and PAN_MAP_ON_ITEM_SELECT. By setting
FILTER_LIST_BY_EXTENT to false, your list will never change, no matter
what you are looking at in the map. If you set PAN_MAP_ON_ITEM_SELECT to
true, the map will pan to the item when it is selected in the list.
These two options allow the short list to be controlled by the list
rather than the map. Also added query string parameters of "extent_filter" and "pan_to_item" to control these configuration options. An example is available here: http://esridotpublic.s3.amazonaws.com/Apps/shortlistwithpan/index.html.