Add scaleToSeconds function

[stivenbb]

Native implementation of scaleToSeconds() Graphite function. (http://graphite.readthedocs.io/en/latest/functions.html#graphite.render.functions.scaleToSeconds)

[shanson7]

See #969 about the generated files. Once that's merged, it will clean up this PR a bit.

[stivenbb]

Speed improvement:

---------- Native scaleToSeconds.json Latencies ----------
Mean: 53.41152ms
50th percentile: 49.204842ms
95th percentile: 78.921391ms
99th percentile: 125.351173ms
Max: 221.644353ms
Success: 100%
Errors: []

---------- Graphite (Python) scaleToSeconds.json Latencies ----------
Mean: 121.113698ms
50th percentile: 112.906348ms
95th percentile: 192.191345ms
99th percentile: 237.401042ms
Max: 395.471465ms

Success: 100%
Errors: []

---------- Speed Improvement ----------
Mean: x2.3
50th percentile: x2.3
95th percentile: x2.4
99th percentile: x1.9
Max: x1.8