Update index.html

Update to V3.1 of d3 library. This link to the old V 3.0 version caused in scripts.js, line 1413 "mapSvg.selectAll('path').attr('d', geoMapPath);" sometimes to many pathSegList points and the neighborhood wasn't correctly clickable then
Create d3.min.js

i got this file from https://github.com/mbostock/d3/releases/v3.1.0/d3-3.1.0.zip today (2014-09-10)
Merge pull request #251 from okilimu/patch-1

Patch 1