contributors logos added to index screen footer
changed hyperlink to funding anchor - added same for the images
old footer removed for index page
removed little underscores appearing between images - caused by link added to images
ENH: Added comparison of other classifiers using partial fit methods
Fixed misc style changes suggested by Ogrisel
first draft of scaling_strategies.rst - still wip
improved scaling_strategies.rst, inc. working links
added Federico as author
cosmit pep8/257
added link to user guide + small cosmit
fix re: ogrisel comments
added note on learning rate evolution
readded a paragraph that got lost in the rebase
COSMIT pep8/257
COSMIT typos
COSMIT typos
added links to plots in narrative docs
ENH SGD Cython improvements

* nogil declarations where possible (but no with nogil blocks, since the
  performance benefit of those is not clear)
* use BLAS where appropriate
* replaced DOUBLE by double, INTEGER and int32 by int/np.intc, since that's
  the type used by scipy.sparse
* explicit checks that dataset dims don't exceed INT_MAX
* replaced an np.all by an explicit loop (npymath library for C99 isfinite)
COSMIT more typos/precisions