Initial Proxy Support

[demon2749]

Created a simple implementation for proxy support. Tested it with Privoxy on my local machine.

If the string is left blank, it doesn't attempt to connect to a proxy.

[demon2749]

PR related to #233

[solaluset]

Thanks, I appreciate your contribution to the project.

Don't we also need to pass proxy to FFmpeg though? And it shouldn't be possible to change it in guild settings since it's a global setting for the bot.