Adding a method to convert a JavaType tp TypeTag

#26: GpuJoinPartition Should be redesigned 

Task-Url: http://github.com/meisam/spark/issues/issue/26
Sending the correct size for right partition to count_join_result kernel

#26: GpuJoinPartition Should be redesigned 

Task-Url: http://github.com/meisam/spark/issues/issue/26
Adding a test case to join Long column types

#26: GpuJoinPartition Should be redesigned 

Task-Url: http://github.com/meisam/spark/issues/issue/26
Joining and copying right partiotion columns from device to host

#26: GpuJoinPartition Should be redesigned 

Task-Url: http://github.com/meisam/spark/issues/issue/26