#24 #31 #31 add CRUD cleanup, additional features

Mimicked spinner dropdown into add_item. Currently needs a method to get
the group name inside DBList.java (it's commented where; also currently
uses hardcoded CS480 string until it is completely implemented). Cleaned
up the UI on each add CRUD activity for slightly better display. Also
renamed listView1 to groupListView inside settings sidedrawer (including
the two dependencies in main). Lightly tested everything and it all
worked.