return proper return code for non testable items

tests/test_apt_proxy.py

@@ -16,7 +16,7 @@ DEF = '\033[0m'
 
 if not os.path.exists('/etc/nginx/sites-enabled/skyreach.conf'):
     print('Server not running CampusManager, skipping test')
-    sys.exit(0)
+    sys.exit(2)
 
 os.chdir(os.path.dirname(__file__))
 if not os.path.isfile('../utils.py'):

tests/test_ssl.py

@@ -16,7 +16,7 @@ DEF = '\033[0m'
 
 if not os.path.isdir('/etc/nginx'):
     print('Nginx not found, skipping test')
-    sys.exit(0)
+    sys.exit(2)
 
 os.chdir(os.path.dirname(__file__))
 if not os.path.isfile('../utils.py'):