Make some important correction

change the value of the pointer object (before was just the array
position +1 but it's not enought)
change clSetKernelArg big error i used arg_index and must be arg_value
change all clRelease, is not very useful but it's clean like that we
release all the element
add bigger sample scan

http://developer.apple.com/library/mac/#samplecode/OpenCL_Parallel_Prefi
x_Sum_Example/Introduction/Intro.html