Electrum client

RFCR @jsutterfield & @garthwebb 

Adds Electrum php client and updates Special:Videos page to use Electrum
Relates to https://github.com/Wikia/electrum/pull/2
I don't know if this is overkill since this is just a prototype, but MediaWiki has an Http class for making curl requests like this. At the very least it would cut down on the boiler plate since I believe you could accomplish lines 84-81 with `$content = Http::request( 'GET', $url, [  'timeout' => self::API_CONNECTION_TIMEOUT ] ) );`