Sending the correct number of tuples

#30: port aggregations from opencl/cuda implementation 

Task-Url: http://github.com/meisam/spark/issues/issue/30
Adding a class to convert MathExpr to C/OpenCL.

The agg_cal call gets an array of struct as input. Each element of the
array represents a mathematical expression in an aggregation. We need to
constructs this array in Java. The java objects cannot be serialized
directly to cunstruct these types. So I am using a custom byte buffer to
enfore LITTLE_ENDIAN encoding of int and long values into the
expressions.

#30: port aggregations from opencl/cuda implementation 

Task-Url: http://github.com/meisam/spark/issues/issue/30
Addign a few sanity tests to make sure Scala/Java works the way I think
Adding more test cases for GPU aggregation

#30: port aggregations from opencl/cuda implementation 

Task-Url: http://github.com/meisam/spark/issues/issue/30
[WIP]: adding a lot of println statements to see what is going on

#30: port aggregations from opencl/cuda implementation 

Task-Url: http://github.com/meisam/spark/issues/issue/30