fix error in (#18): proper workspace allocation in new CuDNN
Merge pull request #18 from JobJob/cudnnR2

Initial support for CuDNN R2 (tested only on OSX)
Merge branch 'tmp'
proper release workspace in CUDA convolution
make CuDNN convolution_forward API consistent with others
remove unused old API
cuDNN pooling support padding now.
update NEWS
make network print out compact
to_array interface for blob
refactor CUDA kernel defs