Add optional SOCKS5 support for HTTP requests

[deadbits]

Added new section to config file:

[proxy]
# set 'use' to True to enable proxy for all HTTP requests
use = False

# proxy must be a SOCKS5 proxy
# proxy must be in host:port format (do NOT add protocol prefix)
http = 127.0.0.1:9050
https = 127.0.0.1:9050

This is ideally meant to be used with Tor, but doesn't have to be. Just any SOCKS5 proxy that can support http and https as the socks5 proxy.

http.py was re-worked to read this configuration data and use these proxies for all web requests if use = True. If the http/https values are invalid, you will receive an Error and the HTTP request (and the module using it) will fail until you address the config error.