Add method to format batch in space using view_converter
Use topo_space stored in view_converter

instead of always trying to build a DefaultViewConverter
Add "convert" arg to FiniteDataSetIterator

FiniteDataSetIterator will only try to format batches in some space
if there is not already a function in convert trying to do that.
Pass to the iterator a convert function using view_converter to format batch
Fix a few tests
Add test that batches returned from iterator are consistent with topo
Add experiment with maxout on cifar10 as test
Merge pull request #418 from lamblin/fix_cifar10_format

Fix cifar10 format