Oasis: Example of Voxel-Based Morphometry.

Hard-coded paths for now since the archive is not online yet and the
downloader is therefore not implemented.
Oasis: downloader ready after data have been uploaded on NITRC.
Oasis: Have the dowloader work + adapt n_subjects in example.
Oasis: remove dead temporary code.
Oasis: Cosmit: address bthirion's comments.
Oasis: Add tests for the downloader + doc.
Oasis: DARTEL-normalized data available.
Oasis: embed Oasis CSV file (needed for tests).
Oasis: DARTEL + modulation.
Oasis: Address GaelVaroquaux and eickenberg comments.
Oasis: fix tests.
Oasis: ANOVA + SVR in examples instead of permuted OLS.
Oasis: (test) try to have Travis build completing without error.
Oasis: magnify ANOVA example.
Oasis: example vbm data (ANOVA + SVR vs mass univariate).
ENH: add a docstring to the VBM example
Merge branch 'pr_186'
DOC: VBM example in carroussel
VBM example: better plots and scores

f_regression needs to be used for regression, and not f_classif