proxyAuthenticationRequired signal is not fired if the application ran as a windows service

1. Start application as windows service.
2. Use a proxy which requires authentication. 
3. Connect to QNetworkAccessManager::proxyAuthenticationRequired signal

Bug:

The websocket can not connect to the url if a proxy server is enabled and the connected slot is not called. 

Possible reason:

The actual proxy information (enabled, host, port) are stored in the following registry path: 

"Computer\HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ProxyServer" 

which belongs to the current user and windows services does not have access to the current_user keys. 

As a result the connection is not built and runs into a timeout. 

Possible solutions:

• **More sophisticated error handling to let the clients know about this issue.
• Impersonate current user to access proxy information.