Added input_space and output_space to DeepComposedAutoencoder

Added input_space and output_space attributes to
DeepComposedAutoencoder.  This is required to use
DeepComposedAutoencoder as a model.
Merge pull request #254 from dansbecker/master

Added input_space and output_space attributes to DeepComposedAutoencoder
started tuple_var
expose Dataset from pylearn2.datasets
make invert a general method of Preprocessor instead of just ZCA
make ZCA_Dataset support not having targets
doc
Composite and Flattener layers
added 'return_all' flag to S3C.random_design_matrix
better error messages
support for monitoring datasets that only support random iteration (such
as infinite data streams)
more complete implementation of CompositeSpace
made sgd support monitoring datasets that don't support sequential
iteration
more non-sequential iteration support
added a date to a deprecation warning
don't seed iterators that don't need it
updates to tuple_var
Merge pull request #256 from goodfeli/master

Support for learning multiple targets from an infinite random data stream
added gpu_pkl_to_cpu_pkl.py
fixed bad shebang