Add a memory_strategy option to masker to shelve their result.
Bug fix: only shelve on demand
Allow transformation of shelved objects
Minor fix
Move and clean multi subject dictionnary learning files
Clean code.
Clean unused code
BUG: update_Vs now unshelve data
Get affine verif opt. in MultiNiftiMasker
FIx little bug in confounds calculation
Clean code.
Merge branch 'dict_l1' of http://github.com/AlexandreAbraham/nilearn into dict_l1

Conflicts:
	nilearn/input_data/multi_nifti_masker.py