Fix background.pagenation.coffee template

Hi,

Thank you for the generator, it made my development quick.
I needed a space here, so I'm sending a fix.

without space, it compiles to:
```js
chrome.tabs.onUpdated.addListener(tabId)(function() {
  return chrome.pageAction.show(tabId);
});
```

with space:
```js
chrome.tabs.onUpdated.addListener(function(tabId) {
  return chrome.pageAction.show(tabId);
});
```