Fix many "duplicate key" errors

- Reset defaults after every test
- Remove individual `after(db.emptydb)` calls
- Fix async.every in groups test
- Update plugin list in socket tests

test/database/sorted.js

@@ -902,8 +902,4 @@ describe('Sorted Set methods', function () {
 			});
 		});
 	});
-
-	after(function (done) {
-		db.emptydb(done);
-	});
 });