add existenceAccessor to scatterplot

This is not a complete fix for #702, but at least it allows reducing multiple
values at once.  (It is still very weird that the valueAccessor is set to
look at part of the key.)
update crossfilter
generate index.html for examples directory

using grunt-fileindex
fix example source link
update stable version
fix broken tag
ask example contributions
back out to grunt-control-jasmine 0.7.0 (stop using master)

we were only using it because of a bad dependency in another module
jasmine 0.8.0/master seems to be creashing outside the geo-choropleth spec
update stock fixture

also those annoying apostrophes
(is there some utf8/character entity conversion going on?)
Allow filters equal to 0 in filter printer

Prior to this patch, if you were filtering on the value 0, the default
filter printer would not display it, so you could end up with, for example,
", 0.05" in the controls when it should actually say "0, 0.05". This patch
checks explicitly for undefined and null filters.
Merge remote-tracking branch 'origin/master' into inovance