Fix colorbar positioning when using 'axes' argument

The fourth argument of add_axes was using y1 instead of a width. Some cosmetic changes too
Merge pull request #301 from lesteve/fix-plotting-with-axes-argument

Fix colorbar positioning when using 'axes' argument
WIP: try to fix the alpha grid
WIP: add a second score to disambiguate
ENH: better verbosity

verbose=1 should simply give us an idea of how the progress is doing
DOC: complete the docstring
MISC: avoid deprecation with new numpy
MISC: minor improvement in example
Merge branch 'master' into sparse-models