Track fully imported downloads in separate history table

New: Improved detection of already imported downloads
Closes #232

frontend/src/Store/Actions/historyActions.js

@@ -131,17 +131,6 @@ export const defaultState = {
         }
       ]
     },
-    {
-      key: 'downloadImported',
-      label: 'Download Imported',
-      filters: [
-        {
-          key: 'eventType',
-          value: '8',
-          type: filterTypes.EQUAL
-        }
-      ]
-    },
     {
       key: 'deleted',
       label: 'Deleted',