Fixed pymel.core.system.referenceQuery function when editStrings and liveEdits flags are given as True the maya.cmds was returning None in which pymel was failing to extend the allEdits variable later on by raising a RuntimeError, now it fixes the edits variable by setting it to and empty list if it is None.
Merge pull request #17 from eoyilmaz/master

Fixed pymel.core.system.referenceQuery function