Fixes to handle existence of default stream_context context

[crodjer]

In my case, the web server runs can access web data through a proxy. So I have to define a default proxy setting for file_get_context to use by stream_context_set_deafult function. So while a file_get_context requires to provide custom context it should do that by changing the default context.

Also, Google OAuth2 response provides email info, so that should be returned as user_data.