Allow building of custom graph widgets via the API

Originally from ticket #15470.

Hi,

I am tasked with leveraging the LM API to create custom widgets. In particular, I am trying to programmatically create custom widgets for Netapp c-mode, in which I can specify specific volume\'s read and write ops as datapoints, and identify IOPS constraint based on existing netapp c-mode policy groups against those volumes. The issue I ran into was that I do not see API support for these types of custom graph widgets. When I pull the API object details for a sample reference widget, I only get these very general properties. Am I missing something with the existing API functionality, or is it that the API functionality isn\'t quite there yet?

id : 5652

description : cMode IO by volume_clone

columnIdx : 1

lastUpdatedBy : sgarcia

name : cMode IO by volume_clone

ord : 0

params : {@{name=graphid; value=4848}, @{name=interval; value=15}, @{name=timescale; value=day}}

lastUpdatedOn : 1404597593

type : cgraph

dashboardId : 798