Fix plot_haxby_anova_svm example
ENH: error capture for wrong session length

Should prevent bugs like in #284
Fix auto threshold in img_plotting.py

Replace + by - to ensure that some voxels pass the threshold
Merge pull request #285 from lesteve/auto-threshold

Fix auto threshold in img_plotting.py
fit-check for Nifti([Labels, Maps])Masker + type in BaseMasker corrected
Merge branch 'master' of github.com:dohmatob/nilearn