Support query parameters in DZI tileSource URL

We have a need to pass a sessionId query parameter to be able to fetch images that may require a session in order to access those images.  Before this change, if the tileSource was set to:
"/path/to/image.xml?param=value"

Subsequent tile URLs would look like "/path/to/image_files/?param=value0/0_0.jpg" which is obviously invalid.  This change extracts any query parameters and appends them (if there are any) onto the tile URLs.