Permuted OLS: Correct the permutation scheme in haxby example.

The mean image per session and per condition is now considered.
Indeed, if no distinction is made, the observations are not exchangeable
across sessions and the permutation scheme is therefore wrong.
Permuted OLS: Address bthirion's comments.
Fetch files mock can fill csv data

For dataset fetching test, it was required to include valid CSV files. The
fetching API now allows the user to give the content of the CSV file as
recarray.
Get rid of oasis CSV file
Merge pull request #189 from VirgileFritsch/clever_permutations

[ENH] Permuted OLS: Correct the permutation scheme in haxby example.
relaxed the numerical constraint in test_signal
more robust test for canica
Merge pull request #197 from bthirion/fix_failures

Fix failures
BUG: Make crop_img work on 4D img
Fix imports to local paths
Merge pull request #200 from alexsavio/master

Fix imports to local paths
DOC: Fix the reference documentation
Merge branch 'master' of github.com:nilearn/nilearn