added uber item to test_data, may conflict with other new test data
Added magic word for "uber" card

* default id for this is "uber"
* may override this with JNDI Environment coastal-hazards.item.uber.id
* context /data/item/uber will return whichever item is set as "uber"
* added mixed theme for when there are more than one theme in an aggregation
* added "uber" itemType for the aggregation items which do not have any information to display in the UI
Wanted to make the documentation a little more clear here
Merge pull request #538 from jiwalker-usgs/master

"uber" card modification