consistency between "aggregationMethod" and "consolidateFunc" names

first one is whisper's name, second one is graphite's
Merge branch 'f_consowhisper'

* f_consowhisper:
  consistency between "aggregationMethod" and "consolidateFunc" names
  pass data-guessed consolidation method through MultiReader
  Send data-guessed consolidation function through pickle
  Take the aggregation method of whisper just for min or max
  Use the consolidate function for min or max series
Merge branch 'f_normalize'

* f_normalize:
  adding test function for normalize()
  Patch for 'normalize' that crashed with empty set
Merge branch 'f_constantline'

* f_constantline:
  adding test function for constantLine()
  Patch for the constantLine function
Merge branch 'f_groupbynodes'

* f_groupbynodes:
  adding groupByNodes() function, same as groupByNode() w/ several nodes

Conflicts:
	webapp/graphite/render/functions.py