Attempt to fix issue 152.

The URL used to fetch the json/png is urlencoded before being sent to the tsd and it's then added to the history but History.newItem() encodes the URL also.

This change:
* removes the decoding done in QueryString.decode() as History.token() will always return a decoded URL and that seems to be the only parameter used in calls to QueryString.decode().
* appends the format and label values unencoded to the URL
* encodes the complete URL before sending the json/png requests
* adds the unencoded URL to the history