Fix bug in Canopy Overlap test and add simple test for InvertIndex
Fix bug in Canopy Overlap test and add simple test for InvertIndex

tfmorris/dedupe,nmiranda/dedupe,davidkunio/dedupe,dedupeio/dedupe-examples,pombredanne/dedupe,dedupeio/dedupe,datamade/dedupe,tfmorris/dedupe,dedupeio/dedupe,pombredanne/dedupe,01-/dedupe,datamade/dedupe,neozhangthe1/dedupe,01-/dedupe,neozhangthe1/dedupe,nmiranda/dedupe,davidkunio/dedupe