Fix separator for BoundOptions query string 

The query string parameter separating the coordinate pairs is incorrect for the `BoundOptions.GetParameters()` method. According to the [Yelp API](http://www.yelp.com/developers/documentation/v2/search_api#searchGBB), the query string should be:

    bounds=sw_latitude,sw_longitude|ne_latitude,ne_longitude

But currently it is implemented as:

    bounds=sw_latitude,sw_longitude,ne_latitude,ne_longitude

This change fixes the query string and adds a test case.