pep8
add docstring and swap parameter order to be the same as make_node
doc cudnn stuff
Now by default, if cuDNN is available, always use it.
better doc
make dnn detect if the library can be loaded.
Better error message when Theano isn't able to use cuDNN
change error type
Always use the tag cudnn
Detect if we are able to init cuDNN handle before auto enable it.
Merge pull request #2239 from nouiz/dnn

Dnn default and doc