Fix for user defined modules not overriding modules from core.

This fix takes into account that powershell modules are somewhat
different than regular modules and have to be kept separate.

lib/ansible/plugins/connection/winrm.py

@@ -52,10 +52,11 @@ from ansible.utils.unicode import to_bytes, to_unicode
 class Connection(ConnectionBase):
     '''WinRM connections over HTTP/HTTPS.'''
 
+    module_implementation_preferences = ('.ps1', '')
+
     def __init__(self,  *args, **kwargs):
 
         self.has_pipelining   = False
-        self.default_suffixes = ['.ps1', '']
         self.protocol         = None
         self.shell_id         = None
         self.delegate         = None