Some email downloads lagging indefinitely

[RNRetailer]

Hi,

Sometimes when I load an email with gmail_client.get_messages it sits there lagging forever until I kill the program.

I think there are a few changes that could mitigate this:

1. Using a better supported library like requests instead of httplib2 for HTTP requests.
2. Adding an optional progress bar when downloading an email.
3. Adding a timeout to skip an email if it takes too long to download.

Please let me know what you think.

Thanks