fix passing host, and hosts with different port for magento

[chrissachs]

I tried to run this code to connect to a local magento installation:

$magento = new \League\OAuth1\Client\Server\Magento(array(
    'host' => 'http://127.0.0.1:8080/',
    'identifier' => 'identifier',
    'secret' => 'secret',
    'callback_uri' => 'http://localhost',
    'admin' => true, // optional, default false
));

• it resulted in an exception as it checked if the host was not set, although it is used later on
• the alternative port was not passed to the base url

[bencorlett]

Awesome! Thanks!