in space._cast(), added cases for when batch is numeric CudaNdarray or symbolic CudaNdarrayType
fixed space._cast() to properly handle numeric and symbolic CudaNdarray batches (i.e. no-op if trying to cast to floatX, TypeError otherwise)
CudaNdarrays only support float32, not theano.config.floatX. Fixed space._cast() accordingly.
fixed VectorSpace._validate_impl(). When calling _valdiate_impl(S) on a symbolic batch S, it was calling validate() on get_debug_values(S), which returns numeric batches. Fixed by replacing that validate() with np_validate().
Merge branch 'updated_format_as' of https://github.com/SuperElectric/pylearn2 into updated_format_as