CON-1780 Implementing new GlobalFooter layout for Venus

Venus redesign new footer implementation.

https://wikia-inc.atlassian.net/browse/CON-1780
I think we can add global variable to enable/disable this extension. 
You can see it here https://github.com/Wikia/config/blob/dev/CommonExtensions.php#L3064

After creating this var, please change checking 'class_exists' to footer global var