Add support for Graphite web minMax function

[carrieedwards]

Is your feature request related to a problem? Please describe.
The minMax() function is implemented in Graphite web, but is missing from CarbonAPI. In order to enable users to be able to use the minMax() function, it needs to be implemented in CarbonAPI.

Describe the solution you'd like
The minMax() function should be implemented in CarbonAPI, with the same functionality as the Graphite web function. The description of the function is as follows:

minMax(seriesList)
Applies the popular min max normalization technique, which takes each point and applies the following normalization transformation to it: normalized = (point - min) / (max - min).

Example:

&target=minMax(Server.instance01.threads.busy)

Additional context
Tests should be added to verify that the functionality matches that of the Graphite web minMax() function.