mod README.md
refactor internal

  * countを無駄にオブジェクトにぶら下げたりしていたところを除去しました
  * READMEをcoffeeとjsのどっちつかず状態からjsに寄せました
  * testやREADMEの`myret = retry()`を`retry = Retry()`に修正しました

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#	modified:   lib/retries.js
#	modified:   src/retries.coffee
#	modified:   test/retries_test.coffee
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