Add basic plainui tests

tests/test_plainui.py

+from .utils import HubPlainUITestCase
+
+
+class GuestTests(HubPlainUITestCase):
+    def test_index(self):
+        response = self.session.get('/index')
+        self.assertEqual(response.status_code, 200)
+
+        response = self.session.get('/me')
+        self.assertEqual(response.status_code, 200)
+        self.assertIn('login', response.url)
+
+
+class UserTests(HubPlainUITestCase):
+    def test_index(self):
+        response = self.admin_session.get('/index')
+        self.assertEqual(response.status_code, 200)
+
+        response = self.admin_session.get('/me')
+        self.assertEqual(response.status_code, 200)
+        self.assertNotIn('logn', response.url)