BF: for the HDF5 storage, we are doomed to stay consistent also with public/private attributes

Proper solution, while still 'serializing' into hdf5, would be to implement
proper __reduce__, __setstate__ functionality throughout the codebase.  This
will be achieved later.  For now this commit would only revert renaming of
__orig_shape into 'protected' _orig_shape of FlattenMapper.  Triggered/tested
using old saved hyperalignment_tutorial_demo dataset
BF(workaround): for introduced since 2.2.0 release pass_attr - define also at class level

See prev commit for more details ;)
ENH: boost pymvpa_hdf5_version (and use string) and store __pymvpa_version__ as well
Merge pull request #209 from yarikoptic/master

Workarounds for HDF5 storage backend