Minor: Use CommonService for permission lookup

- Some changes found in a very old patch :) - drop injection of PermissionsManager in favor of CommonService
- Rename IsEqualByReflectionMatcher's method to something more specific to differentiate it better from Hamcrest's equalTo() matcher

src/test/java/fr/xephi/authme/util/ExceptionUtilsTest.java

@@ -1,6 +1,7 @@
 package fr.xephi.authme.util;
 
 import fr.xephi.authme.ReflectionTestUtils;
+import fr.xephi.authme.TestHelper;
 import org.junit.Test;
 
 import java.util.ConcurrentModificationException;
@@ -51,4 +52,10 @@ public class ExceptionUtilsTest {
         assertThat(resultNpe, nullValue());
         assertThat(resultUoe, sameInstance(uoe));
     }
+
+    @Test
+    public void shouldHaveHiddenConstructor() {
+        // given / when / then
+        TestHelper.validateHasOnlyPrivateEmptyConstructor(ExceptionUtils.class);
+    }
 }