updated README
updated README

addressed numpy installation which closes #77
davidkunio/dedupe,tfmorris/dedupe,pombredanne/dedupe,neozhangthe1/dedupe,tfmorris/dedupe,davidkunio/dedupe,datamade/dedupe,01-/dedupe,datamade/dedupe,pombredanne/dedupe,dedupeio/dedupe,dedupeio/dedupe-examples,nmiranda/dedupe,dedupeio/dedupe,01-/dedupe,nmiranda/dedupe,neozhangthe1/dedupe