Tests: pathlib used where appropriate

Also fixed various pylint errors and style issues.

test/test_reconfigure_tls.py

@@ -3,6 +3,7 @@ import ssl
 import time
 
 import pytest
+
 from unit.applications.tls import ApplicationTLS
 
 prerequisites = {'modules': {'openssl': 'any'}}
@@ -93,6 +94,8 @@ def test_reconfigure_tls_2():
 
     clear_conf()
 
+    success = False
+
     try:
         ssl_sock.do_handshake()
     except ssl.SSLError: