applyByNode incorrectly counts fields

[gringus]

According to Graphite documentation applyByNode function should count fields (nodeNum option) starting from 0, but carbonAPI counts them starting from 1. In other words it means that:

 applyByNode(stats.counts.haproxy.*.*XX, 3, "asPercent(%.5XX, sumSeries(%.*XX))", "%.pct_5XX")

in Graphite would require

applyByNode(stats.counts.haproxy.*.*XX, 4, "asPercent(%.5XX, sumSeries(%.*XX))", "%.pct_5XX")

in CarbonAPI. Please make this consistent with Graphite.

[grzkv]

@justpresident would you consider picking this up since this is replated to #222