Tests: get rid of classes in test files.

Class usage came from the unittest framework and it was always redundant
after migration to the pytest.  This commit removes classes from files
containing tests to make them more readable and understandable.

test/test_status_tls.py

@@ -1,30 +1,31 @@
-from unit.applications.tls import TestApplicationTLS
+from unit.applications.tls import ApplicationTLS
 from unit.status import Status
 
 prerequisites = {'modules': {'openssl': 'any'}}
 
+client = ApplicationTLS()
 
-class TestStatusTLS(TestApplicationTLS):
-    def test_status_tls_requests(self):
-        self.certificate()
 
-        assert 'success' in self.conf(
-            {
-                "listeners": {
-                    "*:7080": {"pass": "routes"},
-                    "*:7081": {
-                        "pass": "routes",
-                        "tls": {"certificate": "default"},
-                    },
+def test_status_tls_requests():
+    client.certificate()
+
+    assert 'success' in client.conf(
+        {
+            "listeners": {
+                "*:7080": {"pass": "routes"},
+                "*:7081": {
+                    "pass": "routes",
+                    "tls": {"certificate": "default"},
                 },
-                "routes": [{"action": {"return": 200}}],
-                "applications": {},
-            }
-        )
+            },
+            "routes": [{"action": {"return": 200}}],
+            "applications": {},
+        }
+    )
 
-        Status.init()
+    Status.init()
 
-        assert self.get()['status'] == 200
-        assert self.get_ssl(port=7081)['status'] == 200
+    assert client.get()['status'] == 200
+    assert client.get_ssl(port=7081)['status'] == 200
 
-        assert Status.get('/requests/total') == 2
+    assert Status.get('/requests/total') == 2