Integrate Personal feed into main Feed class

[criztovyl]

Allows accessing your private feed by specifying it in the constructor like so:

$patreon = new \daemionfox\Patreon\Feed("user@example.com", "1n53cur3");

Also enables to get the logged in user via Feed#getUser(). :)

No WIP this time, so you can just merge it if you like.