Added non registered statistic

restservice/src/main/java/com/plannaplan/controllers/StatisticsController.java

@@ -55,4 +55,15 @@ public class StatisticsController {
         return new ResponseEntity<>(response, HttpStatus.OK);
     }
 
+    /**
+     * @return amount of students not registered to any groups
+     */
+    @PreAuthorize("hasRole('ROLE_DEANERY')")
+    @GetMapping(path = "/users/noregistered")
+    public ResponseEntity<StatisticSimpleNumberResponse> getNonCommisionsAmmounts() {
+        final StatisticSimpleNumberResponse response = new StatisticSimpleNumberResponse(
+                this.userService.getAmmountOfUsersWithNoAssignedGroups());
+        return new ResponseEntity<>(response, HttpStatus.OK);
+    }
+
 }