Upgrade permissions fix

Explicitly removing them is unnecessary (it appears to remove them when updating). Was throwing error 'You cannot remove required permissions.'

src/js/model.js

@@ -214,11 +214,6 @@ function Model() {
     		});
 
 		}
-		if(versionCompare("2.1.3", checkVersion) > 0) {
-			chrome.permissions.remove({
-				permissions: ['<all_urls>', 'clipboardWrite', 'clipboardRead', 'tabs']
-			});
-		}
 
     }