add logout method to AccessClient and test

fh.fd.ci.client/src/main/java/de/fd/fh/network/AccessClient.java

@@ -16,4 +16,8 @@ public interface AccessClient
     @RequestLine("POST /accounts/login")
     @Headers(Utils.AUTHENTICATION_HEADER + ":Basic {authToken}")
     LoginResponse login(@Param("authToken") final String authenticationHeader);
+
+    @RequestLine("POST /accounts/logout")
+    @Headers(Utils.AUTHENTICATION_HEADER + ":Bearer {authToken}")
+    Response logout(@Param("authToken") final String authenticationHeader);
 }

fh.fd.ci.client/src/test/java/de/fd/fh/network/AccessClientTest.java

@@ -73,4 +73,14 @@ class AccessClientTest
 
         assertEquals("Basic testToken", authHeader, "Should use given token.");
     }
+
+    @Test
+    void testLogout()
+    {
+        mockClient.ok(HttpMethod.POST, "/accounts/logout");
+
+        final Response result = client.logout("testToken");
+
+        assertEquals(200, result.status(), "Should return status code 200.");
+    }
 }