remove use of has_edge from cluster.py, and add examples to docstrings. Fixes #186
remove use of has_edge from cluster.py, and add examples to docstrings.
Fixes #186

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extra : convert_revision : svn%3A3ed01bd8-26fb-0310-9e4c-ca1a4053419f/networkx/trunk%401044

ghdk/networkx,ltiao/networkx,nathania/networkx,debsankha/networkx,kernc/networkx,ghdk/networkx,kai5263499/networkx,jfinkels/networkx,bzero/networkx,michaelpacer/networkx,chrisnatali/networkx,aureooms/networkx,ghdk/networkx,kernc/networkx,chrisnatali/networkx,aureooms/networkx,RMKD/networkx,jtorrents/networkx,ionanrozenfeld/networkx,OrkoHunter/networkx,dhimmel/networkx,dmoliveira/networkx,ionanrozenfeld/networkx,blublud/networkx,dhimmel/networkx,wasade/networkx,sharifulgeo/networkx,debsankha/networkx,aureooms/networkx,RMKD/networkx,Sixshaman/networkx,ionanrozenfeld/networkx,jni/networkx,dmoliveira/networkx,jtorrents/networkx,harlowja/networkx,NvanAdrichem/networkx,jakevdp/networkx,debsankha/networkx,dhimmel/networkx,farhaanbukhsh/networkx,farhaanbukhsh/networkx,chrisnatali/networkx,sharifulgeo/networkx,kernc/networkx,cmtm/networkx,RMKD/networkx,dmoliveira/networkx,yashu-seth/networkx,goulu/networkx,SanketDG/networkx,harlowja/networkx,beni55/networkx,andnovar/networkx,sharifulgeo/networkx,bzero/networkx,JamesClough/networkx,bzero/networkx,jakevdp/networkx,jni/networkx,kai5263499/networkx,blublud/networkx,tmilicic/networkx,kai5263499/networkx,harlowja/networkx,nathania/networkx,farhaanbukhsh/networkx,nathania/networkx,blublud/networkx,jcurbelo/networkx,jakevdp/networkx,jni/networkx