Restore options 31

This is a start to #31. it allows the user to save a string in local storage.  Next step sending the token with bid requests.  
Should we:
1. remove `endpoint` and `version` since they aren't used anymore.
2. Change `domain` to `chrome.storage.local.get(data).domain`
3. Change url to `"https://" + @domain + "/"`
?