title: Change WooCommerce Gateway Display Order
body: <p>I goggled a lot but didn't find an answer.</p>
  
  <p>My Problem is : 
  I developed a custom Woo-commerce payment gateway and added it's settings under checkout tab in Woo-commerce settings panel. 
  Now i want that my custom payment gateway should be at top on checkout page. 
  So how i can do that?</p>
  
  <p>I don't want to do that by doing drag and drop on checkout options page.</p>
  
  <p>I want that when i install and active my plug-in then using some action or hook i want to set it at top.</p>
  
  <p>Thanks in Advance.</p>