Add caching of load saved pickled files for datasets.
Fix circular import
Don't cache what isn't under PYLEARN2_DATA_PATH.
Remove timming as now Theano is ~20x faster in that case (for the second call).
Update url to point to the right place.
Allow the buildbot to pass extra parameters
Add missing import
pep8 remove from white list some of the file I changed.
Merge pull request #873 from nouiz/mixed

cache more stuff and disable others.