Fix a problem in WMS GetFeatureInfoRequest

[samwang]

This submission fixes a problem in WMS GetFeatureInfo command request.

The problem is that when sending a WMS GetFeatureInfo request, the command should take "i", "j" parameter which is the pixel location in horizontal and vertical direction should be of a integer. However, previous code format it as a

double value which causes most servers return an exception message stating that

input value format is invalid. This submission fixes this problem.